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 (fig. 567 6). After fertilization the stalk becomes 



El 



FIG. 567. a, Posterior end of Salpa democratica, seen from the 

 ventral side. Stp, Stolo prolifer ; Nu, nucleus. 6, Terminal 

 portion of stol on young chain, strongly magnified ; 0, mouth ; 

 A, cloacal aperture ; N. nervous centre (ganglion) ; Wg, ciliated 

 pit ; Wb, arch of cilia ; End, endostyle ; Af, anus ; Br, gill ; 

 Nu, nucleus ; Ov, ovary ; C, heart, c, Embryo of Salpa 

 democratica (after C. Grobben). EL, ELeoblast ; PI, placenta ; 

 Ph, phavyngeal cavity ; Kl, cloacal cavity. 



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. Leuckartl.c. compare Kowalevski, " Beitrag zur Entwiekelungs- 

 geschichte der Tunicaten." " Entwickelungsgeschichte der Salpen." Nachr. von 

 der li'omgl. Gesellxcli. der Wissensch., Nr. 19, Gb'ttingen, 1868. 



W. Salensky, " Ueber die embryonale Entwickelungsgeschiclite der Salpen,' 

 Zcitsclir.filr niss. ZooL, Tom XXVIL, 1876. 



W. Salensky, " Ueber die Knospung der Salpen." Morpli. Jahrb., lorn. 111., 

 1877. 



