INFUSORIA. 73 



secondary capsules as a testis. The transference 

 of the capsules is then an act of fecundation, and 

 dissection of these bodies when fully developed 

 would seem to corroborate this view, since they 

 are found to contain numerous minute fusiform 

 bodies, the extremities of which are so fine as to 

 be almost invisible. These are said to be sper- 

 matozoa. 



12. Histrll^iition. — The Infusoria are very 

 abundantly distributed over most parts of the 

 globe, nor does there appear to be an}^ remarkable 

 difference, either in aspect or organisation, between 

 the forms of temperate and tropical climes. They 

 are found plentifully in ponds, lakes, rivers, salt 

 marshes and the sea itself, some species, e. g. 

 Chilodon cuculluhts, being common to both fresh 

 and salt water. They occur also in many artifi- 

 cial infusions, and there can be little doubt that 

 several of these animals have been occasionally 

 met with as internal parasites. Those who re- 

 quire Infusoria for microscopic examination may, 

 mthout much difficulty, obtain most of the more 

 remarkable forms, by searching for them diligently 

 in suitable localities, the exact nature of which 

 can only be learned by experience. Thus, the 

 muddy sediment at the bottom of pools may be 

 examined for such species as avoid the light, whilst 

 others, on the contrary, are obtainable only by 

 skimminof the surface of the water. Careful in- 

 spection of the stems and roots of sub-aquatic 

 plants will often reveal the presence of Vorticella, 

 Vaginicolaf Stentor, and other attached forms. 

 The last-mentioned of these is almost \dsible to 

 the naked eye, and the practised observer soon 



