256 



University of California Publications. [Zoology 



female medusa, 

 with amoeboid egg, 

 much enlarged. 



the expense of others. According to May, the latter are usually 



incorporated by a process of cytoplasmic fusion and subsequent 



disintegration of all the nuclei except the egg nucleus;^ rarely, 



however, according to the same author, cells are 



engulfed bodily.- 



i\Iy observations indicate a third process, 

 namely, the incorporation of cells which have 

 previously begun to disintegrate. They are 

 in line here with the observations of Small- 

 Fig. 3. Portion wood ('99) on the transformations occurring 

 of manubrium of j^ ^ells adjacent to definitive ova in F. tiarella. 

 I have found well-formed nuclei within the 

 egg substance also ; but have been unable to 

 distinguish between cytoplasmic fusion and the 

 bodily ingulfment of contiguous cells. 



When full grown, the egg is from .25 to .30 mm. in diameter, 

 broadly ovate when at rest, somewhat flattened, 

 and opaque. A narrow, peripheral zone (ecto- 

 sarc) is distinguished by the absence of yolk 

 granules. The irregularities of outline (Figs. 

 3, 4) which are exhibited before the egg bursts 

 through the attenuated layer of ectoderm in- 

 vesting the ovary, indicate amoeboid movements 

 which are continued in unfertilized eggs often 

 for many hours after they have been laid (Fig. 

 5). Maturation and fertilization were not ob- 

 served. Those eggs, however, which, to judge 

 by their normal development, had been fertil- 

 ized, showed no more inclination to form pseu- 

 dopodia than the blastomeres during the early 

 cleavages. Fig_ 4_ Manu- 



Eggs were laid in the laboratory in I\Iay, brium of female 



June, July, August, September, December, Jan- medusa, with amoe- 

 boid eggs, just be- 



uary, and March, the only months in which ob- 



fore laying. X 58. 



servations were made ; from which it seems prob- 

 able that there is no circmnscribed breeding season. They were 



^Cf. Doflein ('96), for Tubularki larynx. 

 - Cf . Smallwood ('99), for Pennariu tiarella. 



