THEORY OF COAGULATION. 653 



three minutes and a half. He further observed, 

 that when raised to 130, it did not commence 

 before thirteen minutes and a half had elapsed, 

 and was completed in one hour. 



It is therefore evident that, within certain limits, 

 the coagulating power of blood is augmented by 

 raising its temperature above, and diminished by 

 reducing it below the natural standard. As a 

 further proof of this, it is stated by Muller, that 

 during winter, the blood of frogs coagulates very 

 imperfectly. And I may add, from several ob- 

 servations of my own during the winter of 1840-1, 

 that blood of the eel and several other species 

 of fish, requires from ten to fifteen and sometimes 

 thirty minutes to coagulate in a very imperfect 

 manner. Let us then reject the assertion of 

 Magendie, that " blood coagulates alike at all 

 temperatures from 10 to 156 F." The truth is, 

 that notwithstanding the vast number of ex- 

 periments performed by this celebrated physio- 

 logist, he seems never to have inquired how far the 

 process of coagulation is modified by the differ- 

 ence between warm and cold blooded animals.* 



* Yet we are greatly indebted to him for the light which his 

 researches have shed on the influence of various medicinal agents 

 on the vital properties of the blood, many of which, that are con- 

 stantly employed in practice, disorganize its particles, and diminish 

 or prevent its coagulation, out of the body. For example, he has 

 shewn, that sulphuric, nitric, hydrochloric, oxalic, hydrocyanic, 

 phosphoric, arsenious, and many other acids, in small proportions, 

 either prevent or retard its solidification, that it is retarded by 



