240 ON VARIABILITY AND ADAPTATION 



Perhaps here wrongfully I speak for myself, and do not 

 represent the general views of others, but it seems to me that 

 commonly we are apt to regard every functional act of the various 

 tissues as an immediate response to some stimulus, and, doing 

 this, to overlook and neglect the abundant cell activities that 

 are truly automatic on the part of individual cells, and cell- 

 collections or tissues ; are apt not to realize that according to 

 causation there are three orders of cell activities : (1) those 

 determined by nervous stimulation, which we may term neuro- 

 genic ; (2) those determined by direct stimulus of the individual 

 cells by anything modifying their immediate environment — 

 the environmental ; and (3) the automatic, namely, activities 

 which proceed in spite of or despite absence of sustained stimuli, 

 whether neurogenic or environmental. 



Now, it is these last, the automatic activities, to which I 

 would particularly direct your attention — to their nature, their 

 mode of origin, and their relationship to the other two. I 

 believe that when we come to look narrowly we find that they 

 are quite common. It seems to me that the development of 

 cell habit is essentially the development of cell automaticity. 



Primarily, as determined by a study of the lowest unicellular 

 form of life, and of isolated cells of multicellular animals, such 

 as leucocytes, it is external agencies that initiate cell activities ; 

 the nervous system is a higher co-ordinating mechanism de- 

 veloped in multicellular organisms, and so neurogenic cell activi- 

 ties are of secondary and later development. Further, we must 

 regard all automatic activities as not of independent development, 

 but as initiated by the individual cell becoming subjected, in the 

 first place, to either environmental or neurogenic stimuli. To 

 afford a basal instance : the ovum while fully matured lies latent 

 and incapable of growth until such time as a spermatozoon, or, as 

 Loeb has shown, alteration in the tonicity of the surround- 

 ing medium, initiates active nuclear changes ; once initiated, 



fever. While thus Dr. Lichty affords an anatomical basis for the supervention 

 of mucous colitis, it will be seen that his views are not in opposition to the 

 suggestion here put forth, but, on the contrary, tend to confirm it. Dr. Lichty, 

 that is, recognizes that some active disorder leading to lowered vitality and 

 increased congestion is necessary to originate the condition ; that, once origin- 

 ated, the excessive discharge of mucus lasts for weeks and months after the 

 exciting cause has passed away. Accepting Dr. Lichty's views, we may say 

 that the state of chronic congestion of the colon favours the development of 

 the habit of excessive secretion of mucus. 



