458 GEIfEEAL HISTORY OF THE INFUSORIA. 



Mr. Gosse's conclusion (Phil. Trans. 1857, p. 322) is, that " a distinction 

 of sex is the normal condition of the class, or at least of that group which is 

 most typical, viz. such as have articulated mallei working upon a separate 

 articulated incus. Whether the same rule prevails so generally in those which 

 have the mallei and incus fused together into quadi^antic masses, and in those 

 in which the organs exist in a rudimentary condition, is a question yet to be 

 determined. As these are certainly the lowest forms of their class, it is pos- 

 sible that hermaphroditism may be foimd in them — in the Philodinadce, for 

 instance." 



The summary of the facts as yet ascertained, concerning male Rotatoria, 

 will form a valuable addendum to our account : — 



** The most prominent thing that stiikes us is the absolute and universal 

 atrophy (so to speak) of the digestive system in male Rotifera. Another 

 curious peculiarity is the dissimilarity that always exists between the sexes. 

 In Asi^lanchna and Hydatina the resemblance is at its highest point ; in 

 every other instance observed, the sexes are so imlike, that they would be 

 taken for widely-remote genera. The male is always inferior in size, and 

 also in organization, to the female. 



'^Whether certain individuals produce only male, and others only female 

 young, or whether separate impregnations are required for the production of 

 the separate sexes, I do not know ; but from all my observations I gather 

 that the development of the one sex never takes place coetaneously with that 

 of the other ; for male and female eggs are never seen attached to the same 

 parent, and the immatui-e eggs in the ovary invariably develope themselves 

 into the same sex as those which are already extruded. 



" The duration of life in the male is always very brief. I have never been 

 able to preserve one alive for twenty-four hours. Their one business is to 

 impregnate the females, which is the work of a few minutes, probably, in a 

 state of freedom ; and for this momentary occupation no supply of loss, by 

 assimilation of food, is wanted ; and hence we can understand the lack of the 

 nutritive organism. 



" Some organs are found, with greater or less distinctness, in all. The 

 (presumed) male of Hydatina senta received its names of Enteroplea and 

 Organ-fisch from Ehrenberg on account of the copiousness of its internal 

 organization. A muscular system is well developed there, and in the males 

 of Asplanchna and of Bracliionus Midleri ; and, from the varied movements 

 of all, its existence may be inferi'ed where it is not detected. The fi^ontal 

 cilia are, in almost all cases, much more developed than in the females ; the 

 result of which endowment is seen in the excessive rapidity with which the 

 male shoots in all directions through the water. The great head-mass of 

 granular substance is generally distinct ; and in several cases (as in the ^5- 

 jplancJince and in Bracliionus Dorcas and Br. MiUlein) the great occipital gan- 

 glion is well-defined, with the red eye seated on it as in the other sex. Even 

 where the ganglion is not apparent, the eye is conspicuous, with the exception 

 of Sacculus and Polyarthra ; and in this last instance the small size of the 

 animal must be borne in mind, and the density of the anterior parts. 



" In the (presumed) male of Hydatina, in those of all the Asplanchnce, and 

 of Bracliionus Dorcas, there are organs answering to the lateral convoluted 

 threads of the female ; and, in Asplanclina Briglitwellii at least, these are 

 accompanied by tremulous tags, and by a contractile bladder. 



*•' A large mass of substance which, being perfectly opaque, appears black 

 by transmitted light, but is white when the rays are reflected, is so generally 

 found in male Rotifera as to be characteristic, though it is not universally 

 present. I do not find it in the AspJanchncr, nor in Sacculus. On the other 



