174 THE INFLUENCE OZ INANIMATE SURROUNDINGS. 



given the titles of some new works not mentioned by Milne- 

 Edwards. 



V. Power of enduring desiccation. All water animals 

 need a very high degree of moisture in the air or the direct con- 

 tact of water to enable them to live ; if a frog is transferred to 

 dry air, it will quickly part with all its water to the atmosphere 

 and perish of desiccation. 



It has, however, been frequently stated of many water 

 animals that they can endure perfect desiccation without dying. 

 The experiments of Spallans^ni, Duges, Doyere, and others are 

 generally known. Infusoria and certain worms of low type, 

 the Rotatoria, the somewhat high-typed Tardigrada, and various 

 kinds of Crustaceans, are said, according to these observers, to 

 revive after being completely desiccated. The fact that when 

 perfectly dry moss or hay is wetted all sorts of creatures are 

 brought out of it is undoubted ; but Pouchet's experiments 

 account for this in a very simple manner, while, as it seems to 

 me, they strikingly prove that true and complete desiccation 

 infallibly destroys fully grown creatures. He showed that 

 Infusoria, Rotatoria, and Tardigrada, when dried up in the 

 nidus, always die if they are actually and truly desiccated, but 

 that sometimes germs, or it may be eggs, contained in them, 

 and which are protected from utter desiccation by their enve- 

 lopes, on being moistened again develope rapidly, thovigh still 

 enclosed in the desiccated matrix, and creep out. These young 

 animals creeping out from the eggs and germs have apparently 

 been mistaken for the dried- up creatures resuscitated. The ob- 

 servations recorded as to the capability of many animals of the 

 higher orders, even of Yertebrata, for enduring drought are not 

 quite so erroneous ; for it is not asserted that they themselves 

 were desiccated. In tropical countries or in the Mediterranean 

 province, where there is a sharp distinction between the wet 

 and dry season, many animals fall during the latter into what 

 is known as summer sleep. The Protopterus in Africa buries 

 itself in mud, and surrounds itself with a thick perfectly 

 desiccated crust, in which it is able to pass a latent life for 

 months together, till the rain softens the crust and releases the 

 fish. Many land snails attach themselves, during the day or 



