my 



t.musc 



Fig. 440. — Illustrating the development of the genital organs of Aviphioxus lanceolatus. 



( A.fter Boveri. ) 



A, a portion of the body-wall of a young Amphioxus, 9 millimeters long, viewed as a transparent 

 object, in order to sliow the relation of the genital rudiment to the myotomes. B, a small portion of a 

 similar preparation from a still younger specimen, in order to show the origin of the germ cells. C, a 

 small portion of a similar preparation from a slightly older specimen than that from which B is taken, 

 to show the Indentation of the wall of the myotome by the genital rudiment. D, a small portion of a 

 similar preparation from a specimen 14 millimeters long, to show the formation of the gonocoele from 

 the myocoele. E, a portion of a transverse section through a specimen of the same size as that from 

 which D is taken, germ, primitive germ cells ; gon, rudiment of genital organ ; gon.c, gonocoele ; my, 

 myotome ; my.c, myocoele ; scl^, lower sclerotome ; sept, septum, dividing gonocoele from myocoele ; 

 trrmsc, transverse muscle in the floor of the atrial cavity. 



602 



