APPENDIX D. ci 



description, Dr. Arlidge says 1 : ' If this account be 

 correct, the gemmation of Lagenophrys is actually a 

 compound process of budding and fission, whilst the 

 resultant beings differ widely from those of other 

 Vorticellina in all details, and are so very aberrant in 

 form from the parent, that they require to undergo a 

 metamorphosis before they gain it.' 



III. Reproduction by formation of Embryos out of the 

 substance of the ' Nucleus.' 



A. Such development occurring during and after conju- 

 gation of two individuals only (Balbiani). 



a. Embryos may be developed, not in the whole 



nucleus, but in portions of this body which 

 have been separated by previous fission. 

 These generally occur in small numbers ; 

 and in Paramecium bursaria, only one of 

 them undergoes development at the same 

 time 2 . Such an embryo makes its way 

 out of the parent as a tentaculated Acineta, 

 devoid of cilia. 



b. Or the whole of the nucleus may break up, 



preparatory to the development of embryos 

 throughout its substance. 

 In this case, the embryos may be either few 

 or many. According to Balbiani, in the 

 genera Stylonichia and Urostyla the embryos 

 are always four in number, the nucleus 

 being double in each genus. Each nu- 

 cleus divides, and each half of it is meta- 

 morphosed into a single embryo. In the 

 elongated nucleus of Spirostomum ambi- 

 guum, however, about forty or fifty 



1 Pritchard's ' Infusoria,' 4th ed., p. 353. 



2 ' Ann. of Nat. Hist.,' 1858, vol. i. p. 435. 



