364 



SCIENCE. 



[N. S. Vol. II. No. 38. 



declares it to be a study of ' objects before 

 books,' in which " the pupil is directed and 

 set to thinking, investigating and experi- 

 menting for himself." The new method did 

 not fit equally well into all departments of 

 botany, and found its best expression for 

 the most part in developmental and physio- 

 logical subjects. It was in fact the chief 

 agent in preparing the ground for the crop 

 of physiology that is now being sown, and 

 sown in a field selected and staked out by 

 Darwin and Sachs. 



Having shown how the field for the re- 

 ception of the latest botanical husbandry 

 was prepared, I may now briefly trace the 

 soui-ce of the ideas with which it was im- 

 planted, and in doing so it is necessary to 

 point out that vegetable physiology, as the 

 term is generally employed, is not a homo- 

 geneous science. 



The advancement of any subject is pro- 

 moted by a clear understanding of its out- 

 lines, and it is in the interest of clear con- 

 cepts and convenient usage that certain 

 natural limitations should be respected by 

 physiologists. Not that intergradation and 

 mutual dependence do not occur, but that 

 certain natural boundaries may be more or 

 less distinctly recognized which will throw 

 the subject-matter into sections and sim- 

 plify the presentation of the numerous facts 

 of the science. 



The most obvious distinction to be made 

 in the physiological aspect of organisms is 

 in regard to their maturity. The organism 

 in its embryonic or juvenile condition man- 

 ifests functional peculiarities of the highest 

 import, quite unlike those of the adult. 

 The physiology of reproduction belongs 

 here, and includes not only a study of the 

 formation and increase of the young plant, 

 that is, embrj'ology, but genesiology as well, 

 that is, the philosophy of the transmission 

 of qualities and powers from the parent to 

 the offspring, both in vegetative and sexual 

 reproduction. It is a curious fact, which 



Vines has recentlj"^ called attention to, that 

 even vegetative reproduction, as in the case 

 of the growth of a plant from a cutting, 

 brings about rejuvenescence of the proto- 

 plasm, the new individual showing the char- 

 acters of youth, and not of maturity. In 

 both sexual and asexual reproduction the 

 attention should be focused chiefly upon the 

 behavior of the cell, and a wonderful com- 

 plexity will be found in these minute struc- 

 tures. The mystery of a world is bound up 

 in this bit of protoplasm, and correspond- 

 ing to the multuvi in parvo aggregation of 

 properties there seems to be an unsolved 

 intricacj^ of structure. To the study of 

 what was originally supposed to be essen- 

 tially homogeneous protoplasm, we have 

 gradually distributed and extended the 

 properties of the cell to the cytoplasm, the 

 plastids, the nucleus, the nucleoli, the fibril- 

 lar network, the chromosomes, the centro- 

 somes, the kinoplasmic spindle and the 

 polar bodies. What further distribution 

 of function will eventually be found, it is 

 too earlj' in the history of investigation to 

 prognosticate. 



But it is not every dividing cell that 

 points the waj^ to a new individual. Plants 

 with complex structures possess tissues of 

 embryonic character, such as the cambium, 

 whose utmost power of division only leads 

 to the production of additional tissues like 

 those adjoining it, but are wholly incapable 

 of originating a new individual, or even a 

 new organ. From this histogenic extreme 

 all gradations and variations occur, to the 

 perfectlj^ reproductive spore, which by its 

 growth forms another individual without 

 contributing anything to the support of the 

 parent oi'ganism. 



Beside the elementary riddles of life 

 bound up in the processes of cellular repro- 

 duction, or cj'tiogenesis, there are others, 

 relating to nutrition, growth and irritability, 

 which comprise what animal phj'siologists 

 group under the term ' cellular phj-siology,' 



