LARVAL DEVELOPMENT. 



151 



Development of Reprodjictive 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 ram. 



Our knowledge of the details of the processes involved 

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

 work of BovERr, who has made the discovery that the 



met 



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

 individual of 5 mm., to show place of origin of se.xual elements. (After BovERI.) 



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

 Kg. 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 myoccel. 



It had previously been assumed that they were derivatives 



