INFUSORIAL ANIMALCULES. 143 



Infusoria are seen only the one forty-thousandth of an inch in length. 

 What incalculable numbers of animalcules must swarm the waters of 

 creation ! 



Monads vary in their colours, some being red, green, yellow, and 

 others colourless; in shape they are round or oval (5 and 6, fig. 100), 

 and possessed of immense activity, having one or more parts devoted 

 to the purpose of locomotion. Monads have been claimed by the 

 botanist, and accordingly placed among the genus Volvocinece, confer- 

 void algse. Ehrenberg'* regarded and described them as Infusoria. 

 He says : "All true Infusoria, even the smallest monads, are organised 

 animal bodies j some consist of a homogeneous jelly, and are dis- 

 tinctly provided with at least a mouth and internal nutritive appa- 

 ratus." Perceiving small round spots within the bodies of these 

 animalcules, he judged them to be stomachs, in contradiction to the 

 supposition of the former great philosopher in this branch of science, 

 M tiller, in whose work, published in 1773, they were stated to be the 

 animal's eggs. To test the truth of his idea, and convince the world, 

 Ehrenberg fed the little things with colouring matter diffused in the 

 water which contained them. If the water be clear in which the ani- 

 malcule is living, the stomachs are transparent, more so than the other 

 parts of the body ; but are rendered visible by tinting the water with 

 pure sap green, carmine, or indigo. Some of one of these colours is 

 rubbed on a piece of glass, then a few drops of water added ; a portion 

 of the water is then allowed to run off by tilting the glass on one side, 

 and a little of the remainder of the coloured matter dropped into the 

 water containing the animalcule. Portions of the coloured fluid are 

 swallowed by the animalcule, when the stomachs, from their transpa- 

 rency, are distinctly seen of the same colour as the liquid, while the 

 other portions of the body remain unchanged. Some species of the 

 polygastrica have upwards of 100 stomachs, others only four. Sap 

 green is the colour most easily imbibed by the tiny beings ; carmine 

 shows development better than any other ; whilst the indigo, which 

 Ehrenberg found to answer his purpose most satisfactorily, is rather 

 difficult to manage. Care has always to be observed that the colours 

 are not those that chemically combine with water, but only such as are 

 diffusible through the fluid in a state of minute subdivision, as other- 



* Christian Gottfried Ehrenberg, medical counsellor and professor at Berlin, was 

 born at Delitzoch in 1795, and educated at Schulpforta and Leipzig. In 1820-25, he, 

 in company with Hemprich, visited Egypt and Nubia at the expense of the Berlin 

 Academy ; and in 1829 ho accompanied Alexander von Humboldt to the Ural Moun- 

 tains. The results of these journeys he published in various invaluable works, which 

 will hand his name down to posterity with undying honour. 



