OPHIURA BREVISPINA 



415 



tion, however, in the color of the eggs constituting broods pro- 

 duced by different females. The extremes in color noted in the 

 broods of Ophiura eggs are lemon yellow and dark green. 



EARLY DEVELOPMENT 



The egg of Ophiura begins to segment in about one hour after 

 it has been fertilized (extruded into the water). Its cleavage 

 is total and, for a time, equal (text fig. 1, A-E.) In these activi- 

 ties and in the time relations also between the early cleavages 



Text fig. 1 Outline drawings of early segmentation stages of the egg of Ophi- 

 ura brevispina, A-E, and an optical section of the early blastula, F. 



there is ahnost perfect similarity to the same phenomena ob- 

 served in the development of the eggs of species of Ophiocoma, 

 Ophiophilus and other genera which produce eggs of minute 

 size. This close similarity in the early developmental processes 

 of eggs of these two extreme types seems to indicate that cleav- 

 age in Ophiura has been disturbed but little if any by the great 

 increase which has taken place in the yolk supply and size of 

 the egg. That this yolk material is, or at least is correlated 



