200 ^^ MUSCULAR, MOTION, 



h\^ Td^^ ^°'^^' ^^^ refpiralions of the ani^pals denominated '* cold-bjooded/* 

 &re effected differently from 0iofe of high temperature ; in 

 fome of them, as the amphibia of I^innaeus, the lungs receive 

 atmofpheric air, which is arbitrarily retained in large cells, and 

 not alternately, and frequently changed. The fifties, and the 

 teilaceous vermes, have lungs which ej^pofe their blood to 

 water, but whether the water alone, or the atmofpheric air 

 mingled with it furnith the changes in the pulmonary blood;j 

 is not known. 

 m infefts. In moft of the genera of inre6ls, the lungs are oborefcent 



tubes containing air, which, by thefe channels, is carried ta 

 every vafcular part of the body. Some of the vermes of the 

 fimpler conflrudion have no appearance of diftindl organs, but 

 the refpiratory influence is neverlhelefs eflential to <heir ex^* 

 iftence, and it feems to be effected on the furface of the whola 

 body. 



In all the colder animals, the blood contains a fmaller pro- 

 portion of the red colouring particles than in the mammalia, 

 and aves; the red blood is limited to certain portions of the 

 body, and many animals have none of the red particles. 

 Experiment: The following animals were put inio feparate glafs vefTels, 



Cold Wooded each filled with a pound weight of diftilled water, previoufly 

 eluded In wat«r boiled to expel the air, and the veffeis inverted into quickfilver; 

 over mercury, viz. one gold fifty, one frog, two leeches, and one frcQi- water 

 th^^'dieT^ b^ut i''''^^^'^"^^** Thefe animals were confined for feveral days, and 

 no gds was emit- expofed in the fun in the day-time, during the monlh of 

 ted, nor was the j^^^^j.^,^ the temperature being from 43° to 48=", but no air 

 W3ter cn3ngeu» itti i i-i rr i /'/•ii 



bubbles were produced m the velTeis, nor any lentible dnni- 



nution of the water. The frog died on the third day,. the Mi 

 on the fifth, the leeches on the eighth, and the frefti-water 

 mufcle on the thirteenth. This unfyccefsful experiment was 

 made with the hope of afcertaining the changes produced in 

 water by the refpiration of aquatic animals, but the water had 

 not undergone any chemical alteration, 

 Hybemating Animals of the clafs mammalia which hybernate, and become 



animals can live j -j j^^ ^j^^ winter, have at all times a power of fubfifting 



under contined * _ ' o 



rerpiration. under a Confined refpiration, which would dcftroy other ani- 



mals not having this peculiar habit. In all the hybernating 

 reculiarity of mammalia there is a peculiar flru6ture of the heart, and its 

 heart and W^ principal veins; the fuperior cava divides into two trunks; 

 veins. the lefl, pafting over the left auricle of the heart, opens into 



* Mjtilus Anatinus. 



the 



