trees twenty-five years oid-the trees are not twenty-five years old, but the plot has been a peach orchard for twenty-five years, and I feel no hesitancy in saying that I could continue it twenty-five years more if I desired, but it is about time the table was cleaned up, and a new cloth put on. But there are some growers on Catawba Island where the farms are small, and one has but little land, who have for twenty-five years kept their orchards in good condition. But there are other men who cannot do it. They have not learned the proper method of ́feeding the baby, and where the strength of the soil is exhausted it cannot be done. In regard to planting where the yellows have been, I have had but little experience, having had but three or four trees with yellows on my place, but there have been a few in my neighborhood. Where the few I did have were taken out, I replanted them at once, and I haven't seen another case, and in the adjoining orchard the same practice was adopted, and the trees did not have the yellows. In regard to replanting an apple orchard, I think the same rule would hold good. If plenty of plant food is furnished, you will have no trouble in getting a tree to grow where one has grown before. In our own practice we do some pretty severe trimming about this time of year, and in burning our brush we use the burner or crematory, as one of our men calls it. We accumulate a great body of hot coals, and they are taken along on our mudboat, and we have a shovel attached, and when we come to a place where a tree has been taken out, we shovel in some of the coals. We take the trees out in the fall before the foliage is gone, leaving the hole in that condition during the winter, and we find that the ashes with the assistance of the hot coals thrown into that place will start a young tree very nicely.

Professor Selby: I think it is risky in Southern Ohio districts. I do not think there is any risk at all in the Northern Ohio district. You can replace the tree in the same place. Just why it is so I could not say, but it probably is true because of the neglected roadside trees through Southern Ohio. There is not so much risk from the trees that stood there before, but from those around it.

Mr. Riggs: After feeding these young trees with muck and nitrogenous substances, would it not be well to sow. a cover crop that will ripen as soon as possible? And I would like to ask whether nitrate of soda with ground bone or steamed bone would not do as well by the soil?

Mr. Bassett: I am a little afraid of it. That is more like dynamite. It hurries things up too fast.

The President: I am afraid we will have to stop the discussion here, and go on with our program. The next thing is a paper bv Professor Selby on "Factors in Plant Production."

FACTORS IN PLANT PRODUCTION.

BY A. D. SELBY, OHIO AGRICULTURAL EXPERIMENT STATION.

In a discussion of the "Factors of Plant Production," the term "production" is to be taken in a broad sense to mean the objective product of the particular plant under culture. With horticulturists this product is often the fruit borne by the plant, though not exclusively so, since our vegetables show a very wide range of marketable parts and our forage crops, none the less necessary, show a still wider range in the portion of the actual plant which yields us returns. The writer recalls how much interest was shown in the discussion of "The Water Factor in Plant Growth," read at the Delaware meeting of the society in 1903. The stimulus to prepare the present discussion has been supplied by the suggestions made by members at that time and since. If it will help some grower of plants to safer and surer principles by which to guide his practice, it will serve the intended purpose.

THE FACTORS OUTLINED.

The factors of plant production appear to be of two broad classes:

II. The factors external to the plant and which we may call its environment.

I. The factors inherent in the plant itself are a most potent and extensive group of vital forces whose influences are, I fear, but vaguely and imperfectly understood by most horticulturists. Their value to supply the basis of principles to guide the practice has been persistently overlooked and the acceptance of true knowledge has been hinderd or impeded by many notions often founded upon ignorance or upon an equally fallacious and mysterious faith in results due the growers.

To hear our horticultural discussions one might conclude that all these problems could be left to the one who propagates varieties, since varietal discussions are so dominant. Yet a little reflection will show how wide and complex a group of factors with which we really deal. Turning to these we may note:

1. The living plant is a machine to turn water, atmospheric carbon and some essential soil and ash constituents into plant tissues or fruits.

2. The labor of the plant is divided among the several sorts of parts or tissues, viz: the water absorption is done by the root system, the water and food conduction by the hardened ducts, the weight of support falls on the woody trunk or branches or their equivalent tissues in herbs, the labor of storage is variously placed, and the real, delicate, laboratory work of the plant is done in the leaves.

Please to bear in mind the all important water absorption of the roots and the yet more vital elaboration of all the available materials by the work of the leaves acting under the stimuus of the sunlight upon them; the roots are placed in the soil, the sole source of moisture, and the leaves are expanded in the air, which in the sunlight finds its sole source of solar energy. The living cambium layer between these roots and leaves reflects the labor of both.

3. The leaves of the plant are the plant's laboratory and in them especially the newly formed substances are produced.

4. The storage of excess food in the plant takes place in the fruit and in the branches.

60-B. of A.

5. The consumption of stored food by the plant at given times is a corollary of its storage. We must expect that to take place and count when it does so.

6. We may then inquire what is involved on the plant's part in the production of a fruit crop, as of a crop of apples.

II. On the other side of the problem, viz: that of the plant's environment, we must consider something about the following factors:

7.

Sunlight in relation to plant growth.

8. Temperature and the diverse relations of different classes of plants to it. 9. The water supply available.

10. The soil and its contained plant food.

11. The cultivator's part in these external factors.

There is less need to discuss this external or environmental factor side of our problem at this present moment. The chief reason for this is found in the mutual adaptation of the cultivatedt plants to the existing conditions as regards sunlight and temperature particularly.

7-8. We may reassert with confidence the all essential part the solar force of the sun plays in the interesting laboratory of the leaf. We can even measure, in a way, the deficiencies of certain seasons like those of 1895 and 1907, from the point of lack of stimulus by low temperatures and reduced sunlight. I may remark here that I am personally convinced that we shall find many disappointments in our fruit crops next year that will prove clearly traceable to the deficient conditions as to sunshine, etc., for the season of 1907. Under temperatures that are most favorable to our crops we may note the different needs of different plants in this regard. The grasses and certain cereals grow well and flourish exceedingly well under cooler temperatures than will bring heavy fruitfulness to these same cereals or will make good crops for midsummer. This difference in temperature needs explains the early season development of some crops and the late season or midsummer development of others. Maize, potatoes, cucurbits, tobacco and other crops serve to illustrate the crops that need high temperatures.

Another matter to note here is that in times of late summer drought the crop development is often most unexpected. I suggest that here we have the operation of compensating forces, the high temperatures and bright sunlight making up, if that were possible, for the apparent water deficiency.

now.

9. The available water supply, the water factor, need only be mentioned Full discussion is given in the paper mentioned at the outset. The matter of the distribution of available soil moisture is, within bounds, under control of the culturist. No one dare deny the importance of this self-same water factor or its control.

10. The plant food contained in the soil is a matter of high importance, but can hardly receive proper treatment at my hands today. All the essential ash constituents of plants are derived from the soil, in soluble forms, and are taken up in the ascending water-stream in the plant. Without the necessary amounts, however small they may be, of these mineral elements supplied only in this manner, the plant forces fail. Without the small amount of iron also contained therein, cell division would not take place and the plant's chlorophyll would be as powerless. It will perhaps serve our purposes to insist upon this matter of dissolved materials several times mentioned. It is only through the absorbed water required to maintain the plant's ascending water stream that the soil plant food gains entrance to the plant.

11. The cultivator's part in certain external factors like water supply is certainly large and also as to plant food, but normally is small in the control of atmospheric conditions as to temperature and sunshine on outdoor crops.

12.

Summing up all it may be noted that the plant is a product of its inherent or ancestral characters and of its environment in sunshine, temperature, moisture and plant food modified by the cultivator's treatment to conserve all favorable external factors.

I. We can now take up singly the inherent characters of the plant itself: 1 The living plant is, in a sense, a machine, more accurately a living force, by which, under the influence of proper temperature and sunlight, the moisture taken up by the root system from the soil is combined with carbon dioxid found in the air and thus results the creation of the compounds we call carbohydrates, or having hydrogen and oxygen in the proportions found in water. To call the carbohydrates by more familiar names, they are the starches, sugars, cellulose, woody fibre, etc., which go to make the great mass of all our grains, fruits and vegetables, as well as plant tissues.

While these compounds are being created, costly nitrogenous materials are taken up from the soil and are re-elaborated in the plant into the form of vegetable proteids so characteristic of our cereal grains as well as other seed plants. The living plant as a machine or vital force exercises all the activities inherent in the plant nature, yet, as before stated, this work of the machine, as we call it, is only possible in the presence of suitable temperatures and the all essential sunlight or solar force. The energy of the sun may be conceived, therefore, as being abstracted little by little by the leaf green or chlorophyll of the plant's laboratory, separated forever from the sun itself, but reincorporated with these new compounds formed in the plant; we may follow the thought further and conceive these portions of solar energy as being liberated and utilized when these compounds in mind are eaten and digested by man or animals or when decomposed by combustion or decay.

Another matter of very great importance is the part plants play in air purification: the plants utilize the carbon dioxid given off by respiration or by combustion. So that at the same time that the plant performs is service in plant production it adds the other beneficient service of purifying the air for the respiration of man and animals.

What factors will then influence or determine the efficiency of the plant machine? A general statement seems the only one possible.

We may believe safely that whatever agencies or factors the plant possesses by reason of its ancestry or parentage, or by reason of its adaptation to its environment or by reason of its special or local place surroundings will contribute to the products it is able to create and therefore to its productiveness. We are rightly accustomed to state that whatever excellencies the plant may have as a result of its breeding or selection will contribute to its value.

Not only this, but whatever effectiveness this living machine derives from its proper care through culture or fertilizers will show in the final result. Nothing is lost in efforts rightly directed toward increasing the efficiency of this delicately balanced machine. Nothing may be left to chance when dealing with these vital forces thus measurably under control.

2. The labor of the plant, that is, of the machine, is divided among the various portions or parts of the plant which we as plant students call plant tissues. Allusion has already been made to this general division. To illustrate more clearly, the water absorption is practically all done by the roots; therefore, soil plant food is absorbed in solution in the water derived from the soil. While limited amounts of moisture will be absorbed by nearly all living parts when water is sprinkled upon the surface of the part, the actual supply in this manner supplied to growing plants may be regarded as negligible.

In respect to water absorption, it is the fine endings of the roots, including especially the roothairs, and not the surfaces of the larger root branches, which perform the actual absorption. In the matter of the conducting tissues between the roots and leafy crown of the plant, we may mention them briefly. If a branch with leaves is cut off it soon wilts. Do we think death of this branch is so immediate? Certainly not. The sudden wilting is explained by the severing of connection between that branch and the remote water supply of the root system. We may also conceive of the living layer of a fruit tree as consisting of a continuous connection between the root system and the leaves. Over every root-branch, every twig or larger branch and over every part of the trunk is spread this layer of living cells, capable of multiplying by dividing and therefore of growing; we call it the cambium or living layer. But along with this conception of the living layer just presented we must get another thought, that of the comparative inactivity of the outer layer of bark, externally dead, and of the inner wood of the trunk which has also ceased to act. The inner or heart wood's actual presence is, in a way, a menace, since it may harbor parasites in its decaying parts, but there is no way of throwing off this dead wood within and only a limited shedding of the dead bark without. The storage of food in twigs near the buds of the season is a well proved fact; but the condition of this stored food in fall and spring offers great contrasts as to its solubility. To this we must come again later.

3. The leaves of the plant are the very center of the plant's activity. Each active leaf is a sort of laboratory having in the chlorophyll or leaf green of the lamina or blade the agent through which the work is done. Leaf green-chlorophyll! What magic is wrought by it! What physical, intellectual and emotional stimuli are wrapped about the green of the leaves. The changing seasons of our latitude bring back to us the ever new spring each year. We may sympathize with the desert region where spring is not and we rightly scorn the monotonous low level of human life in the tropics, where it may be called continuuous spring!

Anew each year the possibilities of the activity foreshadowed in the new leaves each time put forth bring us back to this amazing blanket of green that is spread alike over the bare earth and the bare trees and we ask what it has in store for us. It has life in store for us; it has possibilities of food, possibilities of delicacies, of luxuries and of necessities in store for us. What more may be said of anything else with which we come in contact?

But to anticipate a moment: whence comes this laboratory of green? Does it spring out of the new growth, the new spring's food for plants and trees? To answer in brief, the spring's covering of green is derived exclusively from food stored up by these plants the previous season-the growth of the early summer by which branches are elongated, buds are opened into flowers and initial fruits are formed, and as a result of which so much appears to take place, is exclusively made possible by using up stored plant food of the year before. So for purposes of explanation, since plant processes are in fact continuous from year to year and from decade to decade, we must take an assumed point of beginning whence we shall pursue our studies. This point for the present will be the unfolded leaves and their many times unfolded mysteries: it may be without effect before eyes that see not of the mysteries behind the mask of chlorophyll.

Given then the newly unfolded green leaf, how does it do its work? It works only under favorable conditions of temperature, as you know the optimum or best temperature for maize, muskmelons, cucumbers, tomatoes, and sweet potatoes is much higher than that for blue grass, timothy, oats and cer