180 Prof. M'lntosh's Notes from the 



Signs of rapid division of the sperm-cells characterized 

 many males in the middle of March, and towards the end 

 of the month the perivisceral cavity formed a vast reservoir 

 for the male elements. The body-walls were stretched, 

 the muscular layers diminished, and the alimentary canal 

 collapsed. The tubes of the segmental organ had also en- 

 larged, so that sperms could readily find issue by the 

 segmental papilla. Though the nuclei of the walls of the 

 organ and its tubes were everywhere distinct, no trace of 

 sperms was at any time found within it, so that they probably 

 escape by rupture of the body- wall, as in allied forms. 



The ova in the various examples throughout March 

 appeared to attain full size and maturity, viz. about '1524 mm., 

 and they were probably shed by rupture of the body-wall, 

 the vast numbers set free, even from a limited area, affording 

 an indication of the almost illimitable resources of nature in 

 the sea. Whether the sexes discharge their elements in situ, 

 or by a terminal pelagic stage could not be ascertained. 

 None were captured in the tow-nets dragged, by day and by 

 night, up stream at ebb-tide, and no indication of any change 

 in the structure of the feet, bristles, or eyes, and no shrivelling 

 of the posterior region of the body as in the very interesting 

 Ceratocephalus Osaicai of Akira Izuka *, common in the 

 estuary of the Sumida River in Tokyo, occurred. If one 

 may hazard a conjecture, it is probable that the sperms and 

 ova are discharged on the sites inhabited by the annelids, and 

 the larva3 by-and-by carried seawards. There is no doubt, 

 however, that, without change in the condition of the feet 

 and bristles, the species is an apt swimmer, progressing 

 through the water swiftly in graceful screw-coils. 



Towards the end of May (29th) and for some time pre- 

 viously signs of degeneration appeared in certain ova, as if 

 they were in process of absorption. These ova were smaller, 

 minutely granular, and with larger oil-globules. The lai-ger 

 ova had lost the germinal vesicle and spot, and transmitted 

 light more readily than formerly. Nothing was seen to 

 suggest the view that certain ova were undergoing develop- 

 ment, for, \Nhen kept in vessels both of sea-water and fre.-li 

 water, they were rapidly disintegrated. 



ISome females at this date have shed all their ova, and are 

 o£ a pale brownish-yellow colour, occasionally wiih a minute 

 dusting of yellow grains along the dorsum. 



Having failed to secure the early larvae by any of the 

 methods alluded to, masses of the clayey mud with the adults 



* Journ. Coll. Sc. Univ. Tokyo, vol. xvii. art. ii. (1902). 



