[vol. 3. Robertson. — 'Embryonic Fission in Crisia. 119 



1.. tes.). Below the stomach of the polypide (/»/.) is a similar 



but larger mass of cells constituting the testis <>t' that animal 

 (tes.). If more of the branch of which Fig. 4 is a section 

 could be shown, each succeeding polypide would be found to 

 possess a corresponding structure. Examination of a series 

 of polypides shows that the development of the testis proceeds 

 with that of the polypide, the lower and hence the older poly- 

 pides possessing the larger testis. 



The spermatozoa, two of which are shown in Fig. 5, maj be 

 found clustered about large cells which arc more or less abun- 

 dant throughout the testis, or may be seen passing in a stream 

 through the testis toward its distal portion, to a point at the 

 base of the tentacles. Their actual egress was not detected, so 



that it is imt known whether it urs through a definite opening 



or only after the degeneration of the polypide, as is the case in 

 most bryozoa. Harmer ('9:!) mentions the escape of the sperma- 

 to/.a of Crisia comula through the aperture of the zocecium, 

 but fails to state whether or not the polypide had degenerated. 

 Ilincks ('80) observed them passing in a stream through the 

 intertentacular organ. The ectoprocts are not thought to have a 

 sperm duct, the sperm escaping presumably through the orifice 

 of a zocecium after the polypide has degenerated. Since in most 

 cases ova and spermatozoa are produced in the same zooecium, 

 either simultaneously or in succession, the necessity for a means 

 of egress so that the one may reach the other is not so important. 

 It is possible that in Crisia they may escape before the death of 

 the polypide, and what evidence I have would indicate that those 

 that mature do so while the polypide is still intact. In exam- 

 ining a quantity of material, however, the scarcity of ripe sper- 

 matozoa is very noticeable. In the spring, at least, the male 

 genital products can be obtained in abundance and in various 

 stages of development, but one searches almost in vain for 

 spermatozoa. In a collection of preparations representing a 

 hundred or more polypides, and made from material obtained 

 during the season when the sexual elements are most abundant, 

 in only one instance was ripe sperm found. Fig. 7 represents a 

 section of living testis in a somewhat advanced stage of devel- 

 opment, showing a typical arrangement and appearance of the 



