190 ON VARIABILITY AND ADAPTATION 



the tissue that has formed its unit. Only now are there in- 

 dications, with the development of finer methods and the relative 

 completion of the work upon mass effects, that physiologists in 

 general are by a natural process gravitating from the study of 

 the tissue, its functions and its chemistry, to that of its com- 

 ponent cells. Physiology is becoming and must inevitably 

 become more cellular. And it is peculiarly fitting that we should 

 inaugurate this discussion in Toronto, in recognition of the 

 pioneer part played by Professor A. B. Macallum in emphasizing 

 the importance of cellular physiology. It is no exaggeration 

 to characterize Professor Macallum's long-continued work upon 

 the nucleus, its histology and its chemistry, as the most im- 

 portant series of contributions to medical science that has 

 proceeded, not merely from Toronto, but from Canada at large ; 

 no exaggeration to refer to him as the first English-speaking 

 physiologist to consecrate his activities to work along these lines. 



It is a sincere pleasure to me, coming from another Canadian 

 city, and occupying in this respect the vantage ground of not 

 being a Torontonian, that I can with propriety direct attention 

 to a matter in which Toronto is among us facile princeps. I 

 take it that in opening this discussion I shall perform the greater 

 service if I devote myself to a rapid review of the various findings 

 which together compel the conclusion that the nucleus is the 

 centre of cell activity, leaving it to those who follow me to enter 

 more particularly into the evidence of one or other order. 



Such a general survey is more especially demanded because, 

 to my knowledge, it has not yet been attempted ; or more cor- 

 rectly, when attempted what I regard as the inevitable con- 

 clusions have not been drawn. While individual workers have 

 demonstrated the controlling powers of the nucleus in one or 

 other respect, there has been a curious disinclination to bring 

 the various orders of data together and deduce their full signifi- 

 cance. But here certain limitations must be introduced. The 

 activities of living matter are to be divided into two categories, 

 intrinsic and extrinsic, or vegetative and functional. The 

 observations which have been made upon the nucleus in con- 

 nexion with the vegetative activities, with cell multiplication and 

 reproduction, are very abundant. To discuss these along with 

 the data bearing upon the role of the nucleus in the functional 

 activities of the cell would make our debate altogether too 



