FROM SIMPLE PERCEPTIBLE MATTER. 567 



I have also made a first attempt to divide the two classes of infu- 

 soria in a greater degree by their internal organs. The nutritive system 

 gives in each of the two classes only four distinctions. According to this, 

 the Pohjgastrica fall into Anentera (possessing no intestine), Cycloccela 

 (with intestines forming a circle), Orthocoela (the intestines straight), and 

 Campi/locoela (the intestines crooked). The Rotatoria fall into Trache- 

 logastrica (long-throated without a belly), Ccelogastrica (long intestine, 

 without belly and with short throat), Gasterodela (with bellies), Tra- 

 cJielocystica (with bladders). The intestine of the latter is very peculiar. 



The Rotatoria alone, according to subsequent observations, may be 

 divided according to their masticatory organs, and fall then into three 

 groups: Agotnphia (without any teeth), of which there are but few; 

 Gymnogomphia (teeth not fastened to anything), — this contains the 

 greatest mass ; Desmogomphia (teeth connected). Those with uncon- 

 nected teeth (^Gymnogomphia^ fall into two great natural and equal 

 divisions, viz. Monogomphia (one-toothed) with a tooth in each jaw, 

 and Polygomphia (many-toothed). Those with connected teeth (Des- 

 mogjmphia), whose teeth are not free but fixed on a cartilaginous base, 

 fall also into two natural divisions, viz. Zygogomphia, with teeth 

 placed in pairs, and Lochogomphia, Avith teeth in rows ; so that the 

 following schema may be made : 

 Agoinphia. Gymnogomphia. Desmogomphia. 



Monogomphia. Polygomphia. Zygogomphia, Lochogomphia. 



I. II. in. ' IV. V. 



I have there stated my opinion as to the employment of these organic 

 differences for the purpose of systematic arrangement. 



I have also in the same paper recorded my observations on the 

 development and production of individuals in the infusoria, particu- 

 larly in regard to time. The result of those observations I consider to 

 be one of the most important of the whole series in this memoir. A 

 single individual of Hydotina senta, one of the Rotatoria which I had 

 described at length, and given an engraving of in my first memoir, I 

 kept separate for the space of eighteen days, during which time I ob- 

 served it with the greatest care, and as it was already developed when 

 I isolated it, and did not die of age but accidentally, we may fix the 

 duration of life at above twenty days. An individual of this kind is, 

 however, capable in every twenty-four to thirty hours of a quadruple 

 increase when the circumstances are i'avourable ; in that space of time 

 it is able to develop four eggs, from the first activity of the ovarium 

 to the creeping out of the young. This quadruple increase, if there 

 is no hindrance, and if the individual animalcule lays forty eggs in ten 

 days, gives in the space of one day in the tenth power (that is on the 

 tenth day) a million in(li\ iduals from one mother, on the eleventh day 

 four millions, on tiie twelfth sixteen millions, and so fortii. Although 

 tlie fecundity of the Rotatoria is the greatest which has ever yet been 



