APPENDIX D. cm 



when the parents were still only half 

 their natural size. 



2. The whole substance of the nucleus 

 may undergo successive segmentations, 

 so as to be entirely converted into 

 embryos. The number of embryos pro- 

 duced is, however, very variable, not 

 only in different species, but, accord- 

 ing to Lachmann 1 , even in the same 

 species. The size of the embryos is 

 always inversely proportionate to their 

 number. 

 b. Animals encysted and stationary. 



Single, or several successive embryos, may 

 be produced within a cavity occupying 

 the situation of the nucleus. 

 This mode of origin of embryos has been de- 

 scribed by Stein as occurring in Chilodon 

 cucullus. The embryo differs much in 

 appearance from its parent, and is precisely 

 similar to Cydidium glaucoma. Indi- 

 viduals of all sizes undergo the process of 

 encystment, and embryos of proportionate 

 size may be produced in any of them. 

 After having given birth to one or more 

 embryos, some Chilodons, according to 

 Stein, pass from their quiescent into an 

 active state. 



The production of Acine tee, as one of the 

 stages in the developmental history of the 

 Vorticellina, also takes place by the pro- 

 cess of which we are now speaking. This 



'Ann. of Nat. Hist.,' 1857, vol. xix. p. 332. 



