PHYSIOLOGICAL RELATIONS OF NUCLEUS AND CYTOPLASM 



in the perivisceral fluid, accompanied by a nurse-cell having a very 



large chromatic nucleus, while that of the egg is smaller and poorer 



inchromatin. As the egg 



completes its growth, the 



nurse-cell dwindles away 



and finally perishes (Fig. 



76). In all these cases 



it is scarcely possible to 



doubt that the egg is in a 



measure relieved of the 



task of elaborating cyto- 



plasmic products by the 



nurse-cell, and that the 



great development of 



the nucleus in the latter 



is correlated with this 



function. 



Regarding the posi- 

 tion and movements of 

 the nucleus, Korschelt 

 reviews many facts 

 pointing toward the 

 same conclusion. Per- 

 haps the most sugges- 

 tive of these relate to < 

 the nucleus of the egg 

 during its ovarian his- 

 tory. In many of the 



J J Fig. 163. Upper portion of the ovary in the earwig For- 



insectS, as in both the fi cu la, showing eggs and nurse-cells. [KORSCHELT.] 

 Cases referred tO above, Below, a portion of the nearly ripe egg (<?), showing deuto- 

 .1 p/rrr r> rl t- fi t- P^ asm ' s P neres an d germinal vesicle (g.v.). Above it lies the 



egg-nucie C nurs e_cell () with its enormous branching nucleus. Twosuc- 



OCCUpieS a Central posi- cessively younger stages of egg and nurse are shown above. 



tion, but as the egg be- 

 gins to grow, it moves to the periphery on the side turned toward 

 the nutritive cells. The same is true in the ovarian eggs of some other 

 animals, good examples of which are afforded by various ccelenterates, 

 e.g. in medusae (Glaus, Hertwig) and actinians (Korschelt, Hertwig), 

 where the germinal vesicle is always near the point of attachment of 

 the egg. Most suggestive of all is the case of the water-beetle Dytis^ 

 ens, in which Korschelt was able to observe the movements and changes 

 of form in the living object. The eggs here lie in a single series alter- 

 nating with chambers of nutritive cells. The latter contain granules 

 which are believed by Korschelt to pass into the egg, perhaps bodily, 

 perhaps by dissolving and entering in a liquid form. At all events, 



