INFUSOEIAI ANIMALCULES. 11 



farinaceous substances ; he having sliown that such stains arc due to 

 the astonishingly rapid development of a monad, therefore called the 

 Monas procUgiosa. — (See Berlin Transactions for 1847). 



We should not omit to mention a very common mistake with 

 respect to seeking after Infusoria. Some persons imagine that if 

 they procure a portion of fetid ditch water, or take a few flowers, 

 and immerse them in a flower glass full of water, they will be fur- 

 nished in a few days with aU the varieties they may desire ; the 

 fact, however, is very different from this. It is true, that in such 

 cases, Infusoria will be found, but they Avill be only of the most 

 ordinary kinds. Those of high interest, either as regards their 

 structure, form, or colour, Uke all the other master- works of Nature 

 and of Natui-e's God, are not so easily attained. Some degree of 

 skill must be exercised for the purpose. But as we shall fully 

 explain this matter in the section on the method of procuring and 

 selecting Infusoria, we need not proceed further with the subject 

 here. 



Section. II. — General External Forms, Coverings, Organs, and 

 Members of Infusoria. — Before entering on the classification of Infu- 

 sorial Animalcules, as determined by their internal structure, it will 

 be well to make a few remarks upon their general appearance and 

 external characters, as exhibited by the microscope. The forms and 

 members of large animals may be said, in one respect, to differ but 

 Httle from each other ; the comparative anatomist being enabled to 

 trace, by easy gradations, one common type throughout the whole, 

 the varieties being occasioned by a greater development of certain 

 parts, and the suppression of others. Such, however, is not the 

 case with Infusoria. The general forms of Infusoria will be best 

 conceived by a reference to the drawings, inasmuch as words would 

 be found insufficient to convey an idea of the vast varieties which 

 they assume. Some are egg-shaped ; others resemble spheres ; 

 others, again, different kinds of fruit, eels, serpents, and many 

 orders of the invertebrated animals, funnels, tops, cylinders, pitchers, 

 wheels, flasks, Sec, &c. 



The covering, or outer tunic, of Infusoria, is of two kinds; the 

 one soft and apparently membranous, yielding to the slightest 

 pressure, and accommodating itsulf to the state of repletion or other- 



