iv AUTHOR'S EXPERIMENTS 187 



much larger proportion than that which is commonly 

 found in the sea. 



These experiments show that animals may be 

 accustomed to live in media which are very different 

 from those which they normally inhabit, provided the 

 change is a gradual one. I performed similar investi- 

 gations some years ago with different animals, 1 with 

 the view of ascertaining whether it may not be gene- 

 rally said that the animals which live close to the sea 

 shore where the fresh water of river and rain must 

 certainly somewhat sweeten the sea water, are more 

 liable than others, inhabiting the sea at greater 

 distances from the coast, to get accustomed to life in 

 fresh water. I first compared the resistance to fresh 

 water of three species of Actinozoa, which were A ctinia 

 mesembryanthemum, Anthea Cereus, and Sagartia 

 parasitica, putting them at first into an aquarium 

 containing six litres of salt water and one and a half 

 of fresh water. All went well. After a few days I 

 increased the proportion of fresh water, and no change 

 was apparent, so that on the seventh day I mixed four 

 and a half litres of sea water with three of fresh water. 

 On the ninth day death came, carrying off one Sagar- 

 tia. A second died on the eleventh day, and on the 

 thirteenth and fifteenth days the two last of this species 



1 Henry de Varigny, Beitrag zum Studium des Einjlusses siissen 

 Wasscrs auf die Seethiere. Centralblait f. Physiologic, 21 January, 1888. 



