94 E. E. JUST. 



copulation of the germ nuclei may be readily followed; but such 

 eggs do not segment nor do they ever develop into swimming 

 forms. 



The Living Egg. 



If insemination be made in a suspension of India ink ground 

 up in sea-water, the jelly formation may be easily followed: it 

 differs but little from the cortical outflow observed in eggs nor- 

 mally laid. All eggs, however, do not secrete this jelly; of these, 

 some remain in the germinal vesicle stage and others go through 

 maturation with all or part of the cortex intact. 



As in the normally inseminated egg (see Just, '15a) no cone is 

 present. More often than in the normally laid egg a broad 

 plateau of cytoplasm marks the point of sperm attachment. 

 The sperm, from one to six, are attached to the membrane above 

 this raised cytoplasm or near it. 



Maturation proceeds about as in the normal egg. At matura- 

 tion stages slightly later than in the normal egg, the sperm may 

 be found in the egg. It moves forward with aster formation. 

 The pronuclei meet, remain apposed for a short time, separate, 

 and fade from view. This is not true of all eggs; for apparently, 

 those in the germinal vesicle stage or in maturation stages with 

 cortex intact never engulf the sperm. Moreover, in many eggs 

 that are in maturation with the cortical layer gone, one cannot 

 find sperm. 



These eggs never divide. At first, 191 1, I thought that this 

 behavior of the egg was due to injury of the worms. Its sig- 

 nificance became clear only after the discovery of the normal 

 method of egg-laying. 



The Sectioned Egg. 



During four seasons eggs have been preserved at three and five 

 minute intervals upward to two hours after insemination in 

 sea-water. Study of the sectioned eggs confirms the findings of 

 the study of living eggs. Many eggs remain ovocytes with sperm 

 attached or not. Those that go through maturation do so with 

 or without jelly formation. Eggs that form jelly are likewise of 

 two classes: those in which sperm are found to have penetrated 

 and those in which no sperm are found. 



