MODIFICATION OF VEGETATIVE AND REPRODUCTIVE FUNCTIONS 415 
attempted such analyses can realize the difficulties to be encountered 
without being told about them. It is not sufficient to make determinations 
on whole plants en masse; the several parts must be considered separately 
in as minute detail as possible, and then all must be related to the whole. 
Particularly is this true in relation to leaves and stems, when investigating 
the carbohydrate situation in a series of tests. Brief reflection will render 
obvious the fallacies of judgment which are likely to arise, especially when 
samples are collected during the day following a period of sunshine. The 
speed of digestion of the more complex carbohydrates (if any have been 
synthesized) and of their translocation is widely variable depending upon 
the other nutrients present. The presence of equal quantities of poly- 
saccharides, indicated by analyses of material taken at any particular 
moment, in itself could by no means be interpreted as indicating an equiva- 
lent rate of synthesis, utilization, or storage of such products. These latter 
points could be determined only by a long series of analyses under varying 
conditions, or through indirect methods quantitatively measuring respira- 
tion, carbon fixation, and the like. Caution must be observed, also, in 
attempting interpretations of the analyses of plants already in any particular 
state or condition, the cause of which it might be desired to determine; 
it is only through the knowledge of a series of effects that causes can be 
deduced. For example, an analysis of fruit buds on any kind of fruit tree 
made during the winter or early spring will not furnish sufficient evidence 
on which to formulate a theory as to the nutrient relations necessary for 
their differentiation or presence. Instead, a number of observations from 
spring to winter are essential, for it is more than probable that the condi- 
tions determining meristematic differentiation are quite different from those 
accompanying the further development of the parts in question after initial 
differentiation, and the conditions for flowering may not be those for fruit 
setting and development. In fact, if our proposals are of any value or are 
true, the conditions for the production of the various results can not be 
the same. 
But it is unnecessary to dwell on the complications of the problem to the 
extent that it may seem too large even for the beginning of an attack. 
The question may be asked, how is any knowledge of the relationships of 
vegetation and reproduction significant to practice? In reply it may be 
stated that it is at the very foundation of the whole matter of plant produc- 
tion, for on it rests the real understanding of such problems as cultivation, 
fertilization, irrigation, propagation, pruning (regeneration), phases of 
disease control, and many others. It has been dangerously easy to suggest 
interpretations of many of the results from these various practices upon a 
hypothetical basis; but, lacking still an abundance of carefully worked out 
experimental evidence, little is to be gained from a mere theoretical con- 
sideration of the probable or possible points involved beyond establishing 
working bases. Certain points of attack become obvious at once to anyone 
