106 



TUNICATA. 



parts are almost always reduced to a capsule enclosing a single egg 

 and surrounded by blood. This capsule opens into the respiratory 

 cavity on the right side, some distance from the nucleus, by a narrow 

 stalk-like duct (tig. 567 b). After fertilization the stalk becomes 



A 



Sip 



El 



FIG. 5i37. ", Posterior end of Sctlpa democrat ica, seen from the 

 ventral .side. Stp, Stolo prolifer ; jV, nucleus, h, Terminal 

 portion of stolon=young chain, strongly magnified ; 0, mouth ; 

 A, cloacal aperture ; jV, nervous centre (ganglion) ; If';/, ciliated 

 pit ; Tf7>, aroh of cilia ; End, endostyle ; Af, anus ; Br, gill ; 

 Nu-, nucleus; Of, ovary'; C, heart, e, Embryo of Kfil^ri 

 ,], ,,,,11-,-ntlca (after C- Grobben). El, Elasoblast ; PI, placenta ; 

 Ph, pharyngeal cavity ; Kl, cloaoal cavity. 



shorter, so that the 

 is in- 

 creasing in size, ap- 

 proaches closer and 

 closer to the lining 

 .of the respiratory 

 cavity, and forms 

 with its capsule a 

 projecting cone in 

 which, as in a brood 

 pouch, the embryonic 

 development takes 

 place.* 



In the course of 

 development a pla- 

 centa is formed be- 

 tween the embryo 



* Besides E. Leuckart I.e. compare Kowalevski. " Beitrag zur Entwiekelungs- 

 geschichte der Tunioaten." " Entwickelungsgeschichte der Salpen." Xm-Jir. run. 

 (In- lidnii/l. GesclUrli . der WiwnxcJt., Nr.'li), Gottingen, 1868. 



W. Salensky, " Ueber die embryonale Entwickelungsgeschichte der Salpen," 

 Zcitsclu'.fur'n-UK. Zonl., Tom XXVII.. 1876. 



W. Salensky, "Ueber die Knospung tier Salpen/' Morpli. JnJirli., Tom. III., 

 1877. 



