€60 Letter of Spallanzani to C. Shielner 



slower than that produced bv the living insects, which ^3;^ 

 effected with singular rapidity. 



You will be astonished when I tell you that a larva, 

 weighing only a i'ew grains, appropriates to itself as much 

 oxygen in the same time as an amphibious animal a thou- 

 sand times as voluminous ; and that this considerable ab- 

 sorption is certainly repeated in an enormous manner in the 

 prodigious number of aerian passages disseminated through- 

 out the bodies of these livinc; beings. 



I extended these experiments to dead fresh-water and 

 luarine fish inclosed in common air. Their size permitted 

 me to make these experiments also on their interior parts 

 after they were separated, such as the intestines, stomach, 

 liver, heart, and ovaria ; but all these parts absorbed the 

 oxygen of the air completelv, like insects and worms. 



One capital point of my rcasearches was to discover the 



f)roportion of atmospheric oxygen absorbed by dead and by 

 iving animals. Water is the natural habitation of fishes; 

 but that which stagnates in a vessel is soon spoiled, and be- 

 comes fatal to these animals, though covered with common 

 air ; consequently, fish imprisoned in this manner suffer in 

 such a situation, w hich is disagreeable to them : they come 

 to breathe at the surface, and perish in a very short time. I 

 have seen several die sooner in water of this kind than when 

 exposed in the open air without any water. 



From these observations useful hints may be deduced in 

 regard to the chemical changes of the air by which water is 

 covered. I should, however, have been altogether incor- 

 rect had I adhered to this method only : I therefore added 

 to it a better, by placing the vessels in which I kept these 

 fishes in a stream of running water, by which means the 

 water in the vessels could be continually renewed. By this 

 method I was able to obtain witli more precision the pro- 

 portions indicated. 



: I observed in amphibious animals after death the same 

 phaenomena as those exhibited by worms, insects, and 

 fishes; but living amphibia gave me other results. I had 

 observed that several of them survived for some days the 

 destruction of their lungs; \Vhich furnished me with an op- 

 portunity of submitting them in that state to my experi- 

 ments, and to remark the precise absorption of the oxygen 

 made by the lungs and by the organ of the skin. I was 

 thus enabled to iQrm a comparison between the oxygen ab- 

 sorbed by these mutilated animals and by those which had 

 not been treated in the same manner. 

 You will see in my boo-k how small is the absoxption of 



oxygcii 



