15 



which is soon absorbed. 1 The gills disappear, the clefts be- 

 come closed by the fusion of their walls, and the blood-vessels 

 which went to them are divided into-those which send blood 

 to the lungs and those which carry mixed blood direct to the 

 body. As the horny beak, used for masticating vegetable 

 food, has been lost, when feeding is resumed it is with the 

 wide mouth of the carnivorous adult frog. 



During the period of both gill and lung respiration, if the 

 tadpole is prevented from coming to the surface of the water, 

 no metamorphosis will take place. Retardation also is effected 

 by keeping them in cold water or away from the light. 



In my aquarium, which I keep in a darkened room in which 

 the air is always cool, tadpoles of the wood-frog have re- 

 mained from early in 1895 until now. Small hinder limbs 

 appeared months ago, but no further metamorphosis is visible. 

 Others captured at the same time and kept under ordinary 

 conditions completed their metamorphosis in from six to eight 

 weeks. 



Classification and List of our Local Species* 



The local fauna is embraced in the following classification : 



Class . — Batrachia . 

 Order. — Salientia. 



Sub-order. — Arcifera. 

 Family I. — Bufonidse. 

 Family II. — Scaphiopidse. 

 Family III.— Hylidse. 



1 At the 1896 Liverpool meeting of the British Association for the 

 Advancement of Science, Sir Joseph Lister called attention to the discov- 

 ery by the Russian naturalist and pathologist, Metchnikoff, that the 

 white blood corpuscles crawl about like amoebae, and like them, receive 

 nutritious materials into their bodies and there digest them. The tad- 

 pole having attained the period for the cyclical change involved in the 

 atrophy of the tail, its materials are absorbed by the white corpuscles, 

 digested and carried to the body for nutrition during the temporary fast 

 of the animal. 



