88 ORGANIZATION OF THE INFUSORIA. 



enclosed within the latter on its detachment from the parent stock. The 

 most remarkable modification of external gemmation is afforded perhaps 

 by certain Opalinidae, in which, as exemplified by the A noplophrya prolifera 

 of Claparede and Lachmann, a long series of buds are developed simulta- 

 neously at the posterior extremity, and become successively detached from 

 the parent zooid after the manner of the buds or " proglottides " of a 

 cestoid worm. A highly remarkable modification of the process of external 

 gemmation is exhibited by the Flagellate type Noctiluca miliaris. Here, 

 as demonstrated more especially by the recent investigations of Cienkowski, 

 the entire subcuticular protoplasm becomes broken up into nodular 

 fragments which are protruded upon the external surface under various 

 conditions of disposition, and are finally liberated from the parent sphere as 

 simple monadiform bodies. 



" Internal gemmation " in its most typical condition may be described as 

 a modification only of the previous process. As in the latter case a portion 

 of the endoplast is separated off and enclosed within a portion of the 

 parent substance, but the gemmule or so-called embryo thus produced 

 is retained within the parental body until matured, in place of remaining 

 affixed to its outer wall. Such typical internal gemmation is most abun- 

 dantly represented among the Tentaculifera, as instanced by the more 

 ordinary Acinetce, and various species of Podophrya and Dendrocometes. 

 A modification of this form of internal gemmation is also undoubtedly 

 represented among those numerous types of the Ciliata, such as Stentor, 

 Spirostomum, and many Vorticellidae in which embryos or, more correctly 

 speaking, internal gemmules become separated from the more or less 

 elongate endoplast, which may be properly characterized in this con- 

 nection as an internal proliferous stolon. In all of these last-named 

 cases it is, however, necessary to remark that the internal gemmules so 

 formed are constructed entirely from the substance of the endoplast, and 

 contain no fragment of the surrounding body-substance. In that peculiar 

 form of reproduction recently recorded by Stein of various Euglenidae, 

 Anisonemidae, and other Flagellata, in which young are produced through 

 the enlargement and subdivision of the endoplastic element into one or 

 more germinal masses, the phenomena manifested closely correspond with 

 those last related, but at the same time lead the way to that more general 

 mode of propagation among the Flagellata which is next described. 



Spornlar Multiplication. 



Under the above-named denomination are correlated by the author all 

 those reproductive phases connected with the assumption by the individual 

 animalcule of a quiescent or encysted condition, accompanied by the subse- 

 quent partition of the entire primitive mass into a greater or less number 

 of spore-like bodies. In those instances in which the sporuloid bodies so 

 produced may be easily reckoned, and do not exceed the numbers of two, 



