460 GENERAL HISTOEY OF THE INEUSORIA. 



the males ; their dissimilarity of figure to that of the females, which, coupled 

 with imperfect examinations or misconception of their interior organization, 

 would readily lead to their institution as new species or genera ; the influ- 

 ence of the j)revalent hypothesis of a hermaphrodite nature, and the conse- 

 quent exclusive search for male organs in the perfect female forms, in which, 

 too, the uncertainty appertaining to the pui^^Dose of several appreciable tissues 

 or organs would tend still further to lead astray ; the short existence of the 

 males, and even that brief life limited, it would seem, to a particular period 

 of the year, the early spring, when such creatures are less sought after ; 

 each and all these are circumstances which have caused the male Rotatoria 

 to be overlooked, and continue to do so. However, the non-recognition of 

 the male animals occurs not only in the case of the Rotatoria, but also of 

 other classes of animals, even more higlily organized and so large as to be 

 capable of examination without the aid of the microscope. Among minuter 

 organisms in which an uncertainty prevails, may be mentioned the Daph- 

 niadce and other Entomostraca, among the majority of genera of which the 

 males are still undetected, nevertheless the bisexual character of the class 

 is admitted. 



The comparative rarity of male Rotatoria admits of an interpretation de- 

 rived from analogy. It is a well-recognized fact, that in several classes of 

 Invertebrata (for example, in Daplmiadce and, among Insecta, in the genus 

 Aphis) several generations succeed one another without the concurrence of 

 a male animal in their production, — a phenomenon well named by Prof. 

 Owen, Parthenogenesis or Virgin-generation. Now it clearly appears that 

 one contact with a male Rotifer may suffice for the fertiHzation of all the 

 germinal cells in any female ovary, and be folloAvcd by their successive de- 

 velopment. To use the language of Prof. Owen, the spermatic force once 

 applied suffices for the impregnation of a multitude of ova, or, in fact, of the 

 whole ovary ; and the fact quoted, of Aphides developed by the immediate 

 action of the spermatic force being in their tiums capable of reproducing 

 others by gemmation without a renewal of that force, warrants the supposi- 

 tion that an analogous phenomenon may exist in the Rotatoria. This analogy 

 is strengthened by Mr. Huxley's interpretation of the natm^e and piu'pose of 

 *' winter " ova, which he beheves to be the instniments of an asexual repro- 

 duction. A portion of the ovary seems to be modified and extruded, and sub- 

 sequently to generate a couple of embrj^os. On the other hand, in the Aphides 

 an internal genninal mass remains within the body, and a portion of it ap- 

 pears to be abstracted by each successive individual produced, imtil at length 

 the spermatic force is exhausted. This internal germinal or reproductive body, 

 the instrument of an asexual generation in the Aphides, is then surely homo- 

 logous with the extruded external generative bodies, or ''ephippial ova," of Ro- 

 tatoria. Such an asexual reproduction impHes a fewness of male beings com- 

 pared with the multitude of young which must be developed by the generative 

 processes. Again, the male Rotatoria are not only developed in smaller numbers 

 than the female, but their whole term of existence is very brief, only long 

 enough to fulfil their generative piu'pose ; and, lastly, they are to be found 

 only at particular seasons, mostly in the spring. 



Another obvious reason for the scarcity of male Rotifera suggests itself, 

 viz. that the social institutions of the class may not be on the monogamous 

 model, but that one little active male may divide his favours among a whole 

 harem of females before he completes his brief career. However this may 

 be, to discover the male of any one species, continuous observation is needed, 

 particularly at certain times of the year ; and it must be confessed that but 

 few Rotatoria have hitherto had their history fully investigated. In most 



