EARLY DEVELOPMENT OF GRAFFILLA. 1 79 



tin- ovary is made up of flattened cells, and one might compare it 

 i rouleau of coins of gradually increa-ing size, the smallest 

 In-ill.: !'' ,tted at the anterior end. The larger cells of the ovary 

 arc produced by the absorption of nutritive material- t'mm the 

 \iiellim- cells, in a manner that will be <K --crilied in tin- IH \t 



ion. 



The vitellarium is an extensive organ, and in the posterior half 

 of i li<- body almost completely envelops tin- inte-tine Fig. 6 . 

 In tin- c.irly stages of its formation the cells are very similar in 

 iliM-i 1,1" tin- ovary, and even in the definitive condition their 

 inn Ic-i II.IM- the characteristics of ovarian nuclei. Tin- <>\.iti.m 

 and \itelline cells are in very close association at the middle 

 die body, and for some little distance anterir t<> thi- 

 tin . ,\.n\ i- overlaid by the yolk cells. 



111. MARLY DEVELOPMENT. 



i \ittr it ion oj the Ova and the Formation of the . :f>sulc. 



In oidiT to be able to understand clearly the mamu r in which 

 tin >\ i .ire nourished and the egg-capsule is formed it i- necessary 

 in i .ill .mention to the characteristic condition in GraffUla <>t the 

 duple\it\ of embryos in each capsule In all of the "Id.-r sta 

 the t\\<> embryos are surrounded by a very thin t ran -parent niein- 

 br.me m -hell inside of which the two ciliated indi\ idnal- m.i\ 

 nm\e .il.niii each other with considerable case. In ! 

 or indci d in any stage of segmentation, this thin -hell in the 

 Mil* if the word does not exist, though the nut'-nin^t 



ii.n nl the yolk is of a consistency such that it servee the 

 ]>ni|M'-e nt a shell, and out of this surface l.t\er the true -hell 

 di'iil'tle dillerentiates. During the cleava. u i- seen 



th.u .1 mi-idt rable mass of yolk surround-- the t\\.. enibrxn- 

 I i( [9 The two embryos may be either clu-i in-. iln-r. \\iih 

 onl\ .1 \ir\- thin intervening layer of yolk. i>r \\idtl\ separated 

 and situated at the extreme opposite end- it the c.ip-nle I igs. 

 In either e\ - ent the most pertinent <|Uc-ii<m thai mie i .in 

 rai-e i- hnw the two embryos have come t<> e\i-t \\ithin the same 



\ i ilk ni.i-s. 



\- \\e have pointed out in the preceding -ec(i>n. the ovaries 

 are at their posterior ends somewhat clo-ely .iiiprovimated on 



