474 F. A. POTTS. 



other individuals of the same species produced about 250 

 before their spermatozoa became exliausted. A closer exami- 

 nation of a similar hermaphiodite led to the discovery that 

 spermatozoa were only produced in one genital gland ; from 

 the other only unfertilised eggs were traced. In half its 

 reproductive system the animal was hermaphrodite, in the 

 other female. A few individuals were also noticed in which 

 both genital glands apparently gave rise to eggs alone and 

 never sperm, 'i'iie species is thus constituted of — (1) pure 

 females (occurring very rarely) ; (-) individuals with one 

 ovai'y and one ovo-tostis ; and (3) full licrrmiplirodites forming 

 the majority of the society. No mention is made of any 

 variation in feitility among this latter class, but we are led 

 to believe that all individuals fall into one or other of three 

 sharply marked categories, according to the condition of their 

 gonads. In the light of the results recorded above for otlier 

 species this seems so remarkable that I think this case should, 

 if possible be re-examined. 



(2) Rhabditis duthiersi. — Thi-ee hermaphrodites were 

 observed, each producing fertilised and sterile eggs simul- 

 taneously, and it is suggested that these were possibh'' semi- 

 hermaphrodites of the type described as occurring in R. 

 marionis. It may, however, be pointed out that in 

 R. gurneyi individuals are found with a similar appearance 

 when the formation of spermatozoa is retarded and does not 

 commence simultaneously on the two sides. 



(8) Rhabditis viguieri. — In this species the proportion 

 of males was the largest met with by Maupas (though falling 

 far short of some of the records for Diplogaster maupasi). 

 Males formed 4 per cent, to 5 per cent, of the total in large 

 cultures, and it is almost certain tliat the proportion would 

 have been larsfer if single individuals had been selected for 

 cultures. 



Of the other individuals some were fetnales, which, when 

 isolated, never produced offspring, but when united with 

 males laid fertile eggs. The larvae from such unions, it is to 

 be regretted, were not kept. Hermaphrodite forms were in 



