POLYGASTRIA. 



17 



Leeuwenhoek was little aware how large a prospect of organic life 

 he was opening to our view, when, in the year 1675, he communi- 

 cated to his scientific friends his discovery of the little bell-shaped 

 animalcule {Jig. 5.), now known as one species of an immense class, 

 and called the Vorticella convallaria. His observations were pub- 

 lished in one of the early numbers of the " Philosophical Transac- 

 tions": * much discussion on the subject ensued, and called forth the 

 wit of the philosophers of the day. However, the records multiplied, 

 and now we have obtained a view of the Infusoria, which shows 

 them to be the most widely diffused and by far the most numerous 

 of all the forms of organised life. Wherever Ehrenberg went in his 

 travels with Humboldt, he there detected with his microscope some of 

 the manifold forms of these animalcules ; and wherever his pupils have 

 repeated his observations, the same phenomena have been presented. 

 Not only in fresh water, but almost over the whole ocean, species of 

 Infusoria abound ; if you catch a drop of water from the spray that 

 rises from the paddle of the steam-boat, in it you will hardly fail, 

 with an adequate magnifying power, to detect some specimens of this 

 class. When Sir James Ross and his companions, in accordance with 

 their directions, took up the film from the surface of the Antarctic 

 Sea, that film, in its dried remains, was found to consist of siliceous 

 cases of the Infusoria ; in the mud brought up from the depths of 

 the ocean, at the highest southern latitudes sounded by the deep-sea 

 line, they were found ; and they have also been detected in the sand 

 adhering to specimens dredged up at Melville Island, by Captain 

 Parry ; so that from north to south poles, and in all intervening 

 latitudes, these animalcules are diffused, and extend the reign of 

 animal life beyond that of the vegetable kingdom. 



You may obtain specimens of Infusoria almost at will. If you 

 skim a small portion of the green matter, which in summer time 

 mantles the surface of a stagnant pool, place a drop of this in 

 the object- holder of a microscope, and examine it with a glass of a 

 quarter of inch focu?, you will find it teeming with animal life ; you 

 will see numerous little objects, of one or other of the forms depicted 

 in these diagrams {figs. 5, 6, 7.), leisurely coursing or darting with 

 rapidity across the field of view, or rolling over, or gyrating on their 

 axes. If you examine in like manner a drop of vrater in which has 

 been infused any vegetable or animal substance, and which contains 

 the particles of such substances in a state of decay or decomposition, 

 you will find such infusions similarly tenanted with these active ani- 



* XVn. p.82l. 

 c 



