SPORULAR MULTIPLICATION. 89 



four, eight, sixteen, or thirty-two, they may be appropriately termed 

 " macrospores," while in those instances in which there is an excess of this 

 last-named number, and may be described as innumerable, they may be con- 

 veniently denominated " microspores." In extreme cases many thousands 

 of these last-named bodies may be included within the parent capsule or 

 " sporocyst," their individual calibre being so minute as to be inappreciable 

 even with the highest constructed powers of the compound microscope. 

 Whether microspores or macrospores, each segmented particle ultimately 

 develops to the parent form. The demonstrated existence to any consider- 

 able extent of this sporular form of multiplication is connected with the 

 results of the most recent investigation, many of the facts testifying to 

 the universal prevalence of such phenomenon being now published, indeed, 

 for the first time. Among the higher orders of the class Infusoria sporular 

 reproduction is comparatively rare, being as yet almost unknown among the 

 groups of the Tentaculifera, while in that of the Ciliata a few stray 

 instances can alone be cited. It is in that lower section of the class dis- 

 tinguished by the flagelliform character of their locomotive appen- 

 dages that spore -formation attains its most vigorous development, it 

 representing among these, in fact, in many instances the most general 

 and prolific form of propagation. Quoting those few instances in which 

 spore-production in its true sense occurs among the Ciliata, mention may 

 be made of Colpoda cuculhilus, in which, as demonstrated by Stein many 

 years since* though then reported as cases of simple encystment the 

 encapsuled zooids became divided into two, four, or eight spore-like bodies 

 or macrospores, each having a separate membranous investment; these 

 give exit to animalcules of smaller size, but which in other respects preserve 

 all the characteristics of the parent form. Phenomena closely corresponding 

 with those related of Colpoda have also been observed by Mr. Carter in 

 the Holotrichous genus Otostoma, and still more recently by the author 

 previously quoted in connection with Prorodon teres and Panophrys flava. 

 The only instance as yet placed on record in which an encysted Ciliate 

 animalcule becomes divided into segments so numerous as to fall within 

 the denomination of microspores is afforded by the type recently described 

 by Fouquet under the title of Ichthyopthiriits multifiliis, the encapsuled 

 zooid in this instance dividing up into at least several hundred spore-like 

 fragments. The products of these spores, when first excluded from their 

 cyst or capsule, differ considerably from the parent animalcule, but by 

 degrees acquire an identical aspect and character. Arriving at the Flagellate 

 section of the infusorial class, the difficulty is rather to indicate types in 

 which a sporuloid phase does not more or less frequently intervene. In 

 consequence of the searching scrutiny that has been directed of late years 

 upon this previously all but neglected group, the life-histories and repro- 

 ductive phenomena of its members are in many instances more completely 

 known than that of the more highly organized Ciliata. 



* 'Die Infusionsthiere,' 1854. 



