2OO Chapters in Modern Botany CHAP. 



alike consist of first embryonic and then developed tissues, 

 the same which in the leaf we have already learned to 

 know as epidermic, fundamental, and fibro-vascular. The 

 study of these in all their forms and modifications, from the 

 physiological and the morphological point of view alternately, 

 the continued analysis of tissues into cells, and the fuller 

 study of this ultimate unit-mass, and of the protoplasm of 

 which it is composed, is the new subscience of histology so 

 important to physiology and morphology alike. Were new 

 chapters (say rather volumes) available, we should work 

 out generalisations of no less interest and value than any 

 preceding ones ; we should study the growth and develop- 

 ment of the plant by the multiplication and differentiation 

 of its primitive embryonic cells ; and we should trace these 

 back to the fertilised parent cell or plant-egg, and though the 

 simple morphology of protoplasm would yield us little, its 

 physiology would carry us far. See CELL of "Chambers," 

 with Bower's Practical Botany as convenient laboratory 

 guide to the larger manuals of Van Tieghem and De Bary, 

 etc. 



It is not, however, with this last product of analysis that 

 our studies would close ; we need a returning physiological 

 synthesis. That is to say, we should trace our initial egg- 

 cell onwards into organism again ; this, however, no longer 

 viewed from without as a specimen or form for analysis, 

 but as a working thought-model, and this in actual growth, 

 change, and evolution. The reader's knowledge of the leaf, 

 for instance, has to be built up into such a mental image. 

 The up-stream of transpiration has not only to be seen 

 by itself, exhaling its rising fountain into unseen spray, the 

 stomata adjusting their openings meanwhile, but this must 

 be combined with a picture of all that we know of the process 

 of assimilation and its resultant downward stream ; so with 

 the whole plant, so with its changes throughout the year, so 



