326 Multiplkatioii of the Ifif'usoria. 



there are some eye-bearing monades ^^Jj'" in diameter. Thus 

 the traces of a nervous system descend to the monades. 



I have extended farther my first endeavour to class the Infu- 

 soria according to their internal organization. The digestive 

 system furnishes, in each of the two classes, only four differences. 

 The Polygastrica fall under the Anentera, those without intes- 

 tine ; the Cyclocaela, those with a circular intestine ; Orthocaela, 

 those with a straight intestine ; and Campylocaela, those with a 

 curved intestine. The Rotatoria fall under the Trachelogas- 

 trica, long-throated without stomach ; Caelogastrica, long intestine 

 without a stomach, and with a short throat ; Gasterodela, those 

 with a stomach ; Trachelocystica, those with bladders. The in- 

 testine of the latter is very peculiar. 



The Rotatoria alone, from my further observations, have 

 been capable of being divided according to their dentary organs. 

 They fall first under three groups : Agomphia, toothless, they 

 are few in number ; Gymnogomphia, free toothed, they are the 

 most numerous ; Desmogomphia, hook-shaped teeth. Those 

 with free teeth fall under two great natural divisions, viz. the 

 Monogomphia with one tooth in each jaw, and the Polygom- 

 phia, with many teeth. The Desmogomphia, whose teeth are 

 not free but inserted into a cartilaginous plate, fall also into two 

 natural subdivisions, the Zygogomphia with teeth disposed in 

 pairs, and Lochogomphia, with teeth in rows, so that the fol- 

 lowing scheme may be formed : 



Agomphia. Gymnogomphia. Desmogomphia. 



Monogomphia. Polygomphia. Zygogomphia. Lochogomphia. 

 I. II. III. IV. V. 



Marvellous Multiplication of the Infusoria, — I have also 

 made 'some observations on the development and multiplica- 

 tion of the Infusoria, which I deem among the most im- 

 portant of all my researches. I have observed for eighteen 

 days successively a single Hydatina senta^ and as it was per- 

 fectly grown when I singled it out, and did not die of old age, 

 being accidentally destroyed, the life of this animal must be 

 more than twenty days. Such an individual, w'heii circutrf-* 

 stances are favourable, is capable of a fourfold propagation everjf 

 twenty-four — thirty hours. It can in this time bring forwardk 



