138 SPONTANEOUS GENERATION. 



conferred the name of Monas lens. As figured and described by this author, 

 the above-named species is distinguished in its more minute form by the 

 two conditions of aggregation just enumerated, his illustrations of them 

 being necessarily on a very small scale, and no trace being indicated or 

 discernible with the instruments at his disposal of the characteristic loco- 

 motive flagella. 



The further development of the separated monadiform corpuscles has 

 yet to be traced. Following the assumption of the independent motile 

 condition, an increment in the size of the constituent body, and with it a 

 duplication of the locomotive appendage, was observed. Within twelve 

 hoars from the first submersion of the hay, many of these bodies had 

 increased to twice their original size, measuring now the i-io,oooth part 

 of an inch in diameter, and possessed in addition to a vibratile appen- 

 dage a second flagellum which trailed posteriorly when the animalcule 

 swam through the water, or held it anchored at will to the vegetable 

 debris or other substances contained in the infusion. Retaining their 

 spheroidal form and two associated flagella, they still continued to increase 

 in bulk, until, at the end of twenty-four hours, the field was more or less 

 crowded with biflagellate animalcules having an average diameter of from 

 the I -3000th to the 1-2 5 00th part of an inch, and exhibiting in their 

 adult state all the characteristics of an ordinary Heteromita. To make the 

 history complete, these adult Heteroniitcs were observed to increase 

 abundantly by simple fission, as also more rarely to unite or coalesce, the 

 product of such fusion being the assumption by the united zooids of a 

 quiescent or encysted state, followed by the breaking up of the combined 

 mass into a heap of minute sporular bodies corresponding with those just 

 described, and which, like them, were subsequently released and recom- 

 menced their developmental cycle under the form of similar irregularly 

 clustered or chain-like aggregations. Heta^oniita lens, however, represented 

 but one, though perhaps the most constant and abundantly developed, 

 out of a number of monad forms that were produced in the various 

 macerations of hay examined, all of which existed, and were for the most 

 part recognizable, in their sporular condition attached to the external 

 surface of the vegetable tissues at the time of their immersion. 



Such other spores of various descriptions were found abundantly 

 scattered among those of the type just described, most of them, as in the 

 case of Heteromita caudata and Oikomonas imitabilis, being of considerably 

 larger dimensions than, and sometimes, as in the first of these two instances, 

 presenting a contour altogether distinct from, the simply spheroidal spores 

 of H. lens. In the last two instances the sporular bodies were produced 

 by the subdivision of the parent animalcule into four, eight, or sixteen 

 segments only, and thus conformed in character with the type designated 

 " macrospores " in the account given of the reproductive phenomena of 

 the Infusoria. In that of Heteromita lens, on the other hand, these cor- 

 responding bodies were so numerous and minute as to baffle computation, 



