The Behavior of Cells 193 



of an Amoeba under the same conditions. Like 

 Amoeba also the leucocytes were found to be nega- 

 tive in their response to light, and when subjected 

 to too high a degree of heat they withdrew their 

 pseudopods and assumed a rounded form. 



It would be of interest to ascertain how the vari- 

 ous other moving cells react to different kinds of 

 stimulation. I have tried the effect of localized 

 mechanical stimulation, light, and heat on pigment 

 cells, epithelial cells and cells from connective tis- 

 sue, but found no reaction to light, no marked ten- 

 dency to crawl away from injurious mechanical stim- 

 uli, but a general tendency to round up under too 

 high a degree of temperature. The freely wan- 

 dering tissue cells do not appear to possess that 

 repertoire of adaptive responses which the leuco- 

 cytes have in common with the Amoeba. Probably 

 fuller investigation will reveal more adaptive be- 

 havior in the cells of tnany forms. We know as 

 yet next to nothing in regard to this field of inquiry, 

 but it is one which promises to afford interesting 

 results. 



In that fascinating group of primitive organisms, 

 the slime molds, formative processes stand in a more 

 obvious relation to cell behavior than in the higher 

 organisms. The coming together of individual cells, 

 their union to form a creeping plasmodium like a 

 gigantic Amoeba, the transformation of this Plas- 

 modium into a definite form characteristic of a par- 

 ticular species, — all thesp processes are for the most 



