THE DISEASES OF CATTLE. 51 



blood away from an animal, we find gas in the arteries, intro- 

 duced there to fill the void left by the flow of blood ; a void 

 ■which is not suffered to pervade the arterial parietes, on account 

 of their not returning with sufficient rapidity to their natural 

 calibre. 



" For a very long time it has been known that, after death, 

 aeriform fluids occupy the place of the blood in the arteries, 

 which has been propelled into the venous system. It was, in- 

 deed, from this discovery of Erudistratus that the arteries re- 

 ceived the name they bear to this day. 



" The presence of gases in the sanguiferous system, and in 

 the interstices of tissues, is never observed, according to M. de 

 Bluinville, in the foetus, before it has respired. He assures us 

 he has never seen globules of air escape from the body of the 

 foetuses, which he has opened under water. Notwithstanding 

 this imposing authority, however, one is tempted to doubt the 

 correctness of the assertion, when one knows that the blood of 

 the mother and the waters of the amnion both contain gas. 



" (B.) Of the Gases of the Generative Cellular Tissue. 



" The presence of gas in the cellular tissue is abundantly 

 jjroved by the formation of emphysema, at times very consid- 

 erable. 



" We find them within the cellular tissue entering into the 

 iomposition of organs, as well as in that which forms the adhe- 

 j-ent surface of serous and ligamentary membranes. 



" Underneath the skin, emphysema, in some cases, makes its 

 appearance spontaneously, or without any appreciable cause : 

 it then seems to be the result of a particular and entirely 

 i.ocal secretion of this tissue. More commonly, however, the 

 accumulation of sub-cutaneous gases depends upon some in- 

 ternal morbid condition, of which it is but the effect or a 

 symptom. Fevers called adynamic and typhoid, and typhus 

 ever, and the introduction through the skin of certain poisons, 

 rurnish examples of this. 



" But the presence of aeriform fluids underneath the skin, 



