CHROMOSOMES AND ECTOPLASM 



environmental factors and the quality and character of 

 the ectoplasmic reaction. Again the Intensity, that is, the 

 strength of the change In the environment, determines the 

 rate of the ectoplasmic response; and within optimum 

 range, this rate determines the degree of the nuclear 

 response. 



Specific examples to support these statements one may 

 find In the literature on fertilization, experimental par- 

 thenogenesis, experiments on cell-division and on develop- 

 ment. I may mention again the observations on the &^g 

 of Chaetopterus which after treatment with hypertonic sea- 

 water develops and differentiates Into an abnormal swim- 

 ming form; here clearly ectoplasmic activity conditions 

 nuclear behavior. In sea-urchins' eggs treated with potas- 

 sium cyanide, the failure of mitosis runs with an exagger- 

 ated activity of the ectoplasm.^ Also, In sea-urchins' 

 eggs, the experimental prolongation of the monaster 

 stage is conditioned by an exaggerated ectoplasmic 

 activity. 



Egg cells have been subjected not only to changes in 

 temperature, In salinity and in hydrogen-Ion concentration 

 of the surrounding sea-water; they have also been exposed 

 to radium, Roentgen and ultra-violet rays. The first 

 noticeable effect of such exposures Is on the ectoplasm. 



Some years ago Packard"' reported results of exposing 

 eggs of Nereis to radium. The first effect observed Is 

 cytoplasmic. In consequence or at least in sequence to 

 this follow modifications in nuclear behavior. Rediield^ 

 especially has analyzed the ectoplasmic response displayed 

 by this egg after exposure to various rays. In this same egg 

 I found that ultra-violet rays induce profound local ecto- 



1 Just, 192 jb. 

 - Packard, 1^14. 

 ^ Redfield, igiS. 



