[17] RETARDING DEVELOPMENT OF SHAD EGGS. 811 



or less actively in obedience to the fluctuations in the activity of this ex- 

 ternal stimulus. All this goes without saying, however, that the pro- 

 toplasm, which in the case of every cell invests the nucleus, may not 

 also share in the process ; it is but natural that it should, because free 

 nuclei, independent of any investment of protoplasm, are unknown to 

 histologists. 



Inasmuch as the granular particles of nuclear fibers and reticuli ex- 

 hibit certain modes of motion which appear to be characteristic in the 

 course of segmentation, and since we find that heat, admittedly a mode 

 of motion, accelerates or retards the motion of living nuclear matter in 

 its segmentational metamorphoses, are we not warranted in assuming 

 both of these kinds of motion to be in a degree correlated and interdepend- 

 ent ? The significance of the views here set forth in their bearings upon 

 general physiology and pathology would appear to warrant the belief that 

 we may yet be able to solve some of the knottiest problems in biology. 

 Their practical significance in relation to the problems which have pre- 

 sented themselves for solution to the Fish Commission will also be ap- 

 parent. 



