370 Dr. R. D. Thomson on Pegmine and Pyropine. 



able to procure such a substance as proteine by following most 

 scrupulously the directions supplied by its original describer, 

 and others who have copied his descriptions. His scepti- 

 cism on this subject originated some years ago when engaged 

 in researches on the brain, an abstract only of which has been 

 published in Liebig's edition of Geiger's Pharmacie. The 

 process of analysis for this intricate combination consisted in 

 dissolving the albuminous part of the nervous system in dilute 

 caustic potash ; a reagent which produces no soluble power 

 on the peculiar matter of the brain, but combines with it, 

 forming an insoluble salt. The potash solution, on being 

 withdrawn from the insoluble matters, yielded by neutraliza- 

 tion with acetic acid, a substance which ought to have been 

 proteine, because it was obtained by precisely the same process 

 as that which has been described as the best for procuring 

 that substance. But on dissolving after washing in potash, 

 adding acetate of lead and boiling, it gave an abundant black 

 precipitate, indicating the presence of sulphur. This experi- 

 ment was shown to Prof. Liebig by the writer at the time 

 (1842), and it is believed that that distinguished chemist con- 

 siders the existence of proteine problematical. 



Pegmine. 



About the same period (four years ago), the writer exa- 

 mined a product of the disease usually known under the name 

 of the bufFy coat of the blood, a coating of a buff colour, which 

 usually exhibits itself on the surface of inflamed blood, and 

 which has attracted much of the attention of writers upon pa- 

 thological subjects. He found it to be a distinct body, and 

 he has been in the habit of describing it in his lectures under 

 the name of 'pegmine (from Tcryyiia, coagulum). It partially 

 dissolves by long-continued boiling in water, but may be 

 washed in cold water, like fibrine, without undergoing any de- 

 composition. It therefore possesses an equal right with fibrine 

 to the character of a body sui generis. When dissolved in 

 potash and precipitated with acetate of lead, and the liquid is 

 boiled, a black precipitate of the sulphuret of lead falls. The 

 following are the results of the analysis of this substance made 

 in 1842, and which the writer has been in the habit of quo- 

 ting in his lectures. 



I. Pegmine containing Fat. 



The first specimen was prepared by simply washing the 

 bufFy coagulum with repeated additions of cold water. It 

 was taken from a patient affected with a violent attack of 



