Prof. Ehrenberg's Researches on the Infusoiia. 213 



mensions, as the Eosphora nqjas and Hydatina senta, and in 

 general all the natural group of the Rotatoria, possess a single 

 cavity of considerable size and oval form, situate in the anterior 

 part of the body ; the Ztjgotrochis nudis would seem to form 

 an exception to the general rule of this division ; for this animal, 

 when filled with colouring matter, presents a slender, spirally 

 convoluted intestine in the centre of the body. In this animal 

 also, the posterior cloacal dilatation is enlarged into a consider- 

 able cavity, which can retain the colouring matter for some time 

 previous to its being discharged by the anus. 



The number of stomachs varies no less than their form. The 

 whole tribe of the Rotatoria, as already observed, possess but a 

 single cavity. In the Monas termo, four can be reckoned*. 



The number of sacs, which are so many distinct digestive 

 cavities, although connected together by a common tube, varies 

 from 1 and 200 down to 36 in many Voi'ticellce. The largest 

 number is in the ParamcBcium chrysalis, Mlill., where it 

 amounts to 120, and yet there is ample space for still more. 



The anus is easily distinguished from the mouth, when the 

 animal is filled with colouring matter, by its discharge from this 

 orifice, in large irregular coherent masses, very different in ap- 

 pearance from the minute state of division in which it enters by 



• Some ingenious speculations might be founded on tiie high degree of 

 attenuation of organized matter in some of these monads. By M. Ehren- 

 berg's measurements the M. termo does not exceed ^j'jj to jjjLj of a line in 

 diameter; and he states that the four stomachs did not occupy half the bulk 

 of the animal. Each stomach must therefore be about jg'jj of a line in dia- 

 meter; and probably is capable of containing a large number of atoms of 

 colouring matter. Estimating, however, one to contain no more than three 

 atoms, and each of these to be of a globular form, this will prove the exist- 

 ence of particles of matter in water not larger than 55555 of a line in diame- 

 ter, or 5 35550 of an inch. 



Some of Dr Ehrenberg's observations tend to prove that the genus Monas 

 and some others are only the young state of some Kolpodce, ParamiecicB, &c. 

 But supposing them to be perfectly developed animals, and that their ova 

 bear the same relation to the size of their bodies, which those of the Kolpoda 

 do, that is, 40 to 1, we must conclude the existence of young monads which 

 have a diameter of only j^bso of ^ line, or yjo'doo of an inch. Each of these 

 monads must possess a stomach and organs passing in dimensions the power 

 of numbers, and certainly giving us very magnificent ideas of the grandeur 

 of organized nature. 



