132 Marvels of Pond-Life. 



My specimens had no visible eyes, and these organs 

 are, according to Pritchard's book, " variable and fuga- 

 cious." The same authority remarks, " In most vital 

 phenomena they very closely accord with the rotatoria ; 

 thus like these they can be revived after being put into 

 hot water at 113° to 118°, but are destroyed by immer- 

 sion in boiling water. They may be gradually heated 

 to 216°, 252°, and even 261°. It is also by their capa- 

 bility of resuscitation after being dried that they are 

 able to sustain their vitality in such localities as the 

 roofs of houses, where at one time they are subjected to 

 great heat and excessive drought, and at another are 

 immersed in water." 



When vital processes are not stopped by excess of 

 temperature, as is the case with the higher animals, the 

 power of resisting heat without destruction depends 

 upon the condition of the albumen. Soluble albumen, 

 or, as it should be called, Albuminate of Soda (for a 

 small quantity of that alkali is present and chemically 

 united with it), after having been thoroughly dried, may 

 be heated without loss of its solubility ; although if the 

 same temperature was applied before it was dry, that 

 solubility would be destroyed, and it would no longer 

 be a fit constituent of a living creature. As Dr. Car- 

 penter observes, this fact is of much interest in ex- 

 plaining the tenacity of life in the Tardigrada. 



The movements of the water-bears, although slow, 

 evince a decided purpose and ability to make all parts 

 work together for one common object; and as might 

 be expected from this fact, and also from the 

 repetition of distinct, although not articulated limbs, 



