OTHER FORMS OF ALTERNATION 171 



as a mere organ of the polypide, we must regard the latter 

 as the second or male zooid ; but the testis may perhaps be 

 more correctly considered, like the ovary, as a distinct 

 sexual bud, having the generative system so enormously 

 predominant as to overrule and replace all the rest of the 

 organization ; this bud, like the ovary-bud, being also uni- 

 sexual, but with a male function."* In support of this 

 view he points out that certain undoubted buds, known by 

 the name of statoblasts, are actually at times produced in 

 the same species by this very part — the funicidus — while 

 in another species the testis is developed more in the situ- 

 ation of the ovary, i.e., from the endocyst. As instances 

 of such a dominant development of the generative system 

 as to supplant that of the other organs, he quotes the males 

 of some Rotifera (Asplanchia) ; and probably still more 

 striking illustrations might be found among the Cirrhipedes. 

 Dr. Allman observes in conclusion, that in this view " the 

 complete comprehension of a Polyzoon will involve the con- 

 ception of a ciliated sac-like embryo as a starting point, and 

 a series of buds, of which the last term will consist of 

 a pair of sexual buds, the others being non-sexual ; from 

 the sexual buds a new embryo, like the first, is again pro- 

 duced, which affords a point of departure for another simi- 

 lar cycle . . . analogies, which would seem to bring 

 the whole series of generation and gemmation within tlie 

 domain of the so-called ' Law of Alternation of Genera- 

 tions.' ""f According to this view a twofold interpolation of 

 gemmation must be recognized in the Polyzoa, first in the 

 protomorphic, and again in the gamomorphic stage — and 

 this over and above the continued pullulation of the polypes, 

 throughout the duration of the typical or orthomorj)hii' 

 phase, by which the ramified structure is formed, known as 

 the polypary or polypidom. It is to this sequence Allman 



* Allman, Op. Cit., p. 41. f Op. Cit., pp., H- J2. 



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