484 APPENDIX. 



terms it serum-casein. On drying, this substance first becomes 

 transparent and viscid, then glistening, hard, and tough, assuming, 

 as Panum strongly urges, a beautiful green colour. Scherer,* under 

 whose direction Panum conducted his experiments, correctly 

 remarks, that^the differences between this substance and albumen 

 depend more on the nature of the fluids in which they occur, on 

 the weakened action of the salts, the great quantity of the water, 

 and the extremely minute disintegration of the separated matter, 

 than on an essential difference in the nature of this substance as 

 compared with ordinary albumen, and that casein is precipitated 

 from concentrated, as well as from dilute solutions, while this sub- 

 stance is only precipitated from very dilute solutions by acetic acid. 

 Panum remarks as characteristic of this substance, that it is preci- 

 pitated from its solutions by carbonic acid : this observation is 

 quite correct, but it stands in direct opposition to the view, that 

 this substance is identical with casein ; for as far as my experience 

 goes, the casein of milk is not precipitated by carbonic acid, 

 although the globulin of the crystalline lens is almost entirely 

 thrown down from its watery solution by carbonic acid. More- 

 over, this substance, which may also be recognised in small quan- 

 tity in the white of egg, presents a much closer resemblance to 

 globulin than to the ordinary casein of milk. Panum has also 

 found more of this substance in the serum of woman's than in that 

 of man's blood (0'3f) ; and it was especially abundant in the serum 

 of women shortly after delivery (from 0*99 to l'25-), 



Although Panum's experiments were very carefully made, and 

 have led to the discovery of many new facts, yet the far less 

 numerous experiments of Moleschott, who treated the serum, after 

 the removal of the albumen by salts and coagulation, with sulphate 

 of magnesia and heat, seem to afford far stronger evidence in favour 

 of the existence of casein in the blood. I will here repeat, that 

 neither Scherer nor I have ever ventured to deny, that in all pro- 

 bability casein exists in the blood ; but until its presence in that 

 fluid is actually proved, we cannot recognise its existence there. 

 The discussion on this point is, however, little more than a war 

 of words, for how can we strictly identify a substance with casein 

 when we do not know^what casein* actually is, or rather believe 

 that it is a mixture of two or more substances ? 



M. S. Schultzef has found a matter coagulable in the cold by 

 acetic acid in the interstitial juice of the middle coat of the arteries, 



* Jahresber. d. ges. Med. 1851, S. 75. 



t Ann. d. Ch. u. Pharm. Bd. 71, S. 217. 



