466 E. A. POTTS. 



seen to a stage, sometimes extendiug over several days, 

 daring which eggs passed into the uterus and degenerated. 

 Later, liowever, the amorphous egg material was expelled 

 and its place taken by fertile eggt^ which continued to be 

 produced in large numbers. In this species, one could easily 

 see, the hermaphroditism was not protandrous, but the 

 formation of spermatozoa was sometimes delayed till a number 

 of eggs had ripened. In some cases, it is true, fertile eggs 

 are produced from the first onset of Ujaturity, and at first 

 sight there is nothing to distinguish such forms from the 

 typical protandrous hermaphi'odite found in other species. 

 But beside such an introductory period of infertility, there 

 may be later interruptions of egg-production, which indicate 

 a failure of the stock of spermatozoa. Frequently this is 

 but temporary, and the worm begins again to lay fertile 

 eggs. ^o short sometimes is the duration of sterility that 

 it is indicated only by the ejection of one or two disorganised 

 eggs, and very often only one gonad contains a supply of 

 spermatozoa while they are lacking in the other. 



It is, then, suggested by the culture observations, and fully 

 borne out by examination of the glands under high powers of 

 the microscope, that eggs and spermatozoa come to maturity 

 more or less alternately throughout the period of reproductive 

 activity. 



Structure of the Gland. — In the general form of the 

 reproductive glands of R. gurneyi there is no departure 

 from that described above for other species of the genus. At 

 various periods of development the arrangement of the histo- 

 logical elements differs rather widely from the typical pro- 

 tandrous gland. Text-fig. 9 shows part of the reproductive 

 organ of a hermaphrodite which has just attained maturity. 

 It will be seen that reproductive activity commenced with 

 the formation of a very small number of spermatozoa (sj).^). 

 And after the maturation of a single egg {(>i\^) a more 

 numerous succession of spermatozoa {s-p.'~ and s}).^) \Vas pro- 

 duced, only briefly interrupted by the appearance of another 

 single egg {ov.~) which has not yet reached the limit of its 



