LARVAL DEVELOPMENT. 



Development of Reproductive Organs. 



One of the most interesting events which we have now 

 to chronicle is the development of the reproductive organs. 

 This commences when the young Amphioxus has reached 

 the length of about 5 mm. 



Our knowledge of the details of the processes involved 

 in the formation of the genital organs is again due to the 

 work of BOVERI, who has made the discovery that the 



do- 



tntf 



Fig. 85. Transverse section through the pharyngeal region of a young 

 individual of 5 mm., to show place of origin of sexual elements. (After BOVERI.) 



f. Fascia, e.c. Portion of ccelom, which will form the endostylar coelom. 

 tig. Primitive sexual cells in the lower angle of the myoccel. Other letters as above. 



primitive sexual cells arise in the cavity of the myotome 

 by differentiation of certain of the epithelial cells lining 

 the myocosl. 



It had previously been assumed that they were derivatives 



