110 RESPIRATION OF FISHES. 



Dr. B. And how much more astonishing it is that 

 Europeans who have been accustomed to warmer cli- 

 mates, should be able by using the proper precautions, 

 to bear such severe cold, with equal impunity. The 

 English, at one of their trading houses on the Churchill 

 river, experienced, one year, such a degree of cold that 

 brandy froze in the rooms where they had fires. 



Emily. Ledyard, I recollect, experienced in Yak- 

 utsk, Siberia, a degree of cold which coagulated strong 

 cogm'ac brandy. 



Dr. 13. Many more observations of a similar kind 

 might be mentioned, but these are sufficient to show how 

 independent of external changes, is the temperature of 

 our bodies. 



I will now describe to you how the function of respira- 

 tion is managed in fishes. They cannot obtain access to 

 the atmosphere, it is true, but there is always a quantity 

 of air mixed with the water in which they live, and they 

 are furnished with organs fitted for separating it and ap- 

 plying it to the same purpose as the lungs of animals. 

 Instead of lungs in the interior of their body, they are 

 provided on e?ch side of the neck with several thin, red 

 laminae of a semi-circular form, called branchiae or gills. 

 These are attached to the bones and covered with a 

 moveable lid. In these gills are ramified the extremi- 

 ties of the pulmonary arteries and veins, and also the 

 capillary vessels in which the necessary changes are 

 wrought on the blood. 



Emily. I have heard that if fishes were kept in close 

 vessels, and communication with the atmosphere cutoff 

 they would soon die, but never knew before that it was 

 for lack of air ; for I suppose their death is produced in 

 consequence of all the air in the water being consumed. 

 But is it not strange that they should die so soon when 

 taken out of the water, merely because they breathe 

 pure air, and not air in combination with water ? 



Dr. B. This is sufficient to produce their death, for 

 their respiratory organs are constructed for breathing air 



