348 THE president's address. 



from the nucleus, but it cannot initiate digestion, nor can it 

 ingest food. Many Protozoa, such as Foraminifera, have shells 

 of complicated structure, and if the shell be damaged the animal 

 repairs the injury ; but if its nucleus be removed the power of 

 repairing injuries is lost. On the other hand, if a fragment 

 cub off from a living organism contains the nucleus, or even a 

 portion of the nucleus in some cases, it is able to continue living 

 in a suitable environment, to feed, grow and finally regenerate 

 the entire organism. 



From the data obtained from experiment and observation 

 alike, it is clear that the chromatin-substance is of the greatest 

 importance in the life of the organism. Without it the cytoplasm 

 cannot continue to live and cannot initiate the most characteristic 

 activities of the living substance ; the processes of assimilation 

 and growth, reproduction and sex, all are dependent alike on the 

 presence of chromatin in the protoplasm and cannot take place 

 without it. Speaking for myself, I believe that it is the chromatin- 

 substance which represents the primary living matter, the true 

 material basis of life, and that the cytoplasm is of secondary 

 importance in this respect. 



The objection will doubtless be raised to the view that I have 

 expressed, that, in the case of a unicellular organism, such as an 

 amoeba or a ciliate infusorian, the nucleus isolated from the cyto- 

 plasm cannot live by itself and cannot regenerate the body unless 

 a certain amount of cytoplasm be associated with it. This fact 

 becomes perfectly intelligible, however, when we reflect that 

 many organisms in Nature are so adapted and attuned, so to 

 speak, to a particular mode of life that they cannot live except 

 in certain conditions of environment, or unless supplied with 

 special food. It would therefore be in no way remarkable if a 

 nucleus, living always in a particular cytoplasmic environment, 

 were unable to continue living when removed from its natural 

 surroundings. The fact would not, in my opinion, disprove my 

 contention that the nucleus that is to say, the chromatin is the 

 primary living substance, any more than the fact that a fish 

 cannot live out of water would be a proof that the water was 

 living as well as the fish. 



The most convincing proof, to my mind, that the chromatin is 

 the primary living substance, is that many organisms appear to 

 consist mainly, if not entirely, of chromatin alone, as for example 



