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. 5676). After fertilization the stalk becomes 



Wb 



Sip 



El 



FIG. 507. a, Posterior end of Salpa democratica, seen from the 

 ventral side. Stp, Sto]o prolifer ; Nu, nucleus, b, Terminal 

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

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

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

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

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

 Ph, pharyngeal cavity ; Kl, cloacal cavity. 



shorter, so that the 

 egg, which 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 znr EntwickeluDgs- 

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

 der Hnigl. Gesellsch. der Wissensch., Nr. 19, Gottingen, 188. 



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

 Zeitsclir.fur miss. Zool., Tom XXVII., 1876. 



W. Salensky, " Ueber die Knospung der Salpen." Morph. Jahrb., Tom. III.,' 

 1877. 





