XVII 



PKOTOCHOKDATA 



629 



upper, sterile portion of the rudiment of the ovary. In this genus 

 there is, there fore,, a right and a left ovary, and a right and a left 



ot 



hyp 



oes 



FIG. 457. Illustrating the development of the genital organs in the simple Ascidian 

 )[<>l<jula ampidloides. (After De Sel ys-Longchamps and Damas. ) 



A, young Ascidian seen from the side showing first trace of the genital organs. B, the genital 

 rudiment of an older specimen showing incipient differentiation into ovary testes. C, transverse section 

 through a genital rudiment of a still older specimen showing the hollow ovary and the solid testes. D, 

 a considerably older genital rudiment showing the formation of ampullae by the testes. a, anus ; /, 

 atrial cavity ; endst, endostyle ; ;/un, rudiment of genital organ ; gsl, gs*, the lirst two gill-slits ; hyp, 

 hypophysial canal ; int, intestine ; m, mouth ; oes, oesophagus ; ot, otolith ; ov, ovary ; st, stomach ; 

 /. test'-s. 



testis. It must he remembered that in dona there is only one ovary 

 and one testis. 



