152 M. Dutrochet on the 



quent in all seasons, and the difference in quantity between 

 these is not considerable. In the islands and on the western 

 shores the rain is most abundant in autumn, and pretty abund- 

 ant in winter ; in the interior of the continent it is the sum- 

 mer which presents the greatest amount of rain. The coasts 

 of the Baltic exhibit intermediate relations in this i:espect. 

 The annual quantity of rain depends more especially on proxi- 

 mity to mountains. In the great northern plain of Europe, 

 while the annual quantity augments towards the Atlantic, it 

 only presents slight differences ; but its increase becomes very 

 considerable as we advance from the plains towards the se- 

 condary and less elevated masses of mountains (for example, 

 the Vosges and the Sudetic mountains), and it is still greater 

 towards the great systems (the Alps and the Scandinavian 

 system). The largest quantities known are those of some 

 places on the northern slope of the Alps and the Apennines ; 

 and on the western slope of the Scandinavian system, and of 

 the mountains of the British Islands.* 



Researches on the Vital Heat of Cold-blooded Animals. 

 By M. Dutrochet. 



Animals may be divided into two great sections in reference 

 to the degree of their vital heat. 1. Those of a high tempera- 

 ture — the so-called warm-blooded, — a section containing birds 

 and mamraifera ; 2dly5 those of a low temperature, — the cold- 

 blooded, — a section including reptiles, fishes, and all inverte- 

 brate animals. The vital heat of animals of a high tempera- 

 ture can be easily determined, because it is usually much above 

 the temperature of the surrounding medium. It is otherwise 

 with animals of a low temperature; and is very difficult to de- 

 termine, on account of its slight elevation above the surround- 

 ing medium, the temperature which the animal acquires, and 

 to which it adds that which is peculiar to itself. I shall not 

 here consider all the difficulties which must be overcome, in 



* These general conclusions axe given by Processor Schouw in tlie Atlas 

 prepared for his work on Italy by Captain O. N. Olsen.— Editor. 



