INFUSORIAL ANIMALCULES. 37 



we take into consideration the minuteness of these 

 creatures, the largest not exceeding the 1-lOOth of an 

 inch, wliilst some of them are scarcely l-12th of that 

 size, our ideas of computation are too limited to form any- 

 just notion of the number which sometimes illuminate 

 many miles in extent of the ocean's surface. 



Section XII. — On the Relative Number or Abundance of 

 different Infusoria. 



It has been stated that some species of Infusorial 

 animalcules are more commonly met with than others, 

 and occur in greater numbers. In the List of Species, 

 inserted at the end of this part, those marked with a 

 single (*) thus, are common in vegetable infusions, while 

 those with (* *) thus, are more abundant, and those with a 

 greater number of stars attached to their respective names 

 are still more universally found. 



The most numerous in animal infusions are those of 

 the Monas crepusculum. Spirillum undula, Vibrio regula, 

 Leucophrys carnium, and Polytoma uvella ; in sea water, 

 the Paramecium milium and the Stylonychia. 



Section XIII. — On the Method of Feeding Infusoria with 

 Coloured Substances. 



Select for this purpose such coloured substances as are 

 entirely free from metallic oxides, and not chemically 

 soluble in water. They must, however, be capable of a 



