ON FURTHER OBSERVATIONS ON MALE ROTIFERS. 511 



to the female at various points, thus confirming what had 

 been stated by Dr. F. Cohn.* Plate calls it hypodermic 

 impreg7iatio7i.f We separately repeated Gosse's experiment, 

 but with £. pala instead of B. rubens. We saw a male swim 

 round a female in the manner described by Gosse, but saw 

 nothing we could describe as coitus. But Mr. Marks saw on 

 seven occasions the foot introduced into the anterior cavity 

 of the lorica, and remain attached for periods of over a 

 minute. A similar action was independently seen in one 

 instance by Mr. Wesche, but the female was moribund, if 

 not dead. On the other hand, Mr. Wesche has a note of 

 having seen the coitus of B. angularis in December, 1901. Con- 

 nection was made at the tail orifice (cloaca), and the male 

 and female remained together for approximately a minute. 

 When they separated, a thread was seen to proceed from the 

 toe of the male and connect the two animals. Dr. Plate 

 concluded from his observations that '' uninterrupted partheno- 

 genesis prevailed among the Potifera, and that the male was a 

 vestigial and superfluous sex, and that the abortive attempts at 

 impregnation were an atavistic phenomenon without significance 

 in the life history of the species." % 



Certainly our observations tend to confirm Dr. Plate's, but 

 with the great diversity in the organisation of males it would 

 be cjuite premature to conclude that an observation which only 

 aflfected two or three species bore on the whole order. On the 

 other hand, E. Maupas claims to have proved that the pro- 

 duction of the resting egg depends on fertilisation by the male, 

 which quite upsets Dr. Plate's generalisation. § 



Dr. P. Lauterborn came to the conclusion that the appearance 

 of the male, and consequent production of the resting egg, is 

 " normally recurrent in the life cycle of each species, after a 

 certain definite number of parthenogenetic generations." He 

 further notes, and our observations quite bear him out, " that 



* "Ueber die Fortpflanzung der Rotatorien," ZeiUcli.f. Wiss. Zool., vii., 

 p. 431, 1856. 



•j- " Beitrage zur Naturgeschichte der Rotatorien," Jena. Zeitsch. /. Naturw., 

 xix., p. 63, 1885. 



\ " Beitrage zur Naturgeschichte der Rotatorien," Jena. Zeitsch. f. Naturw., 

 xix., p. 37, 1885. 



§ " Comptes rendus," Ac. Sci., 1890, p. 310. 



