368 



Prof. Carnelley and Mr. T. Wilson. [Feb. 16, 



at all in the ash, or a very dubious trace, due probably to imperfect 

 extraction. 



The ash always contains iron, and the iron is not removed from the 

 precipitate by extraction with alcohol containing hydrochloric acid. 

 This description applies equally to the fibrinogen obtained from the 

 tissues and the fibrinogens present in blood.* 



Under appropriate conditions these fibrinogens can be entirely con- 

 verted into fibrin. The fibrin always contains lecithin ; but fibrin 

 differs from the fibrinogens from which it is formed by being abso- 

 lutely and entirely soluble in artificial gastric juice. This remarkable 

 difference in the behaviour of the two classes of substances towards 

 artificial gastric juice is considered by the author as strong evidence 

 that the relation between the lecithin and the proteid which both 

 bodies contain must be different in the two cases. 



That lecithin was a very important factor in coagulation was shown 

 by the author many years ago, and this fact has been fully confirmed 

 by pupils of Alexander Schmidt (Nauck, Samson-Himmelstjerna, 

 Kriiger) . 



Ordinary fibrin obtained by whipping blood always leaves an undi- 

 gested residue, due partly to the presence of admixed white corpuscles 

 (Hammarsten), partly, however, to its containing unchanged fibrino- 

 gen. Fibrin obtained from pure fibrinogen fluids by artificially 

 induced coagulation is always completely digestible if care be taken 

 that it contains no unchanged fibrinogen. The fibrin obtained by the 

 action of ferment on fibrinogen is always completely digestible 

 (Hammarsten). 



II. "A new Method for determining the Number of Micro- 

 organisms in Air." By Professor Carnelley, D.Sc, and 

 Thos. Wilson, University College, Dundee. Communi- 

 cated by Sir Henry Roscoe, F.R.S. Received February 3, 

 1888. 



(Abstract.) 



This is a modification of Hesse's well-known process. It consists 

 essentially in the substitution of a flat- bottomed conical flask for a 

 Hesse's tube. Its chief advantages are : — -(1.) Much smaller cost of 

 flask and fittings as compared with Hesse's tubes ; (2.) Very many 

 fewer breakages during sterilisation ; (3.) Great economy in jelly ; 

 (4) Freedom from leakage during sterilisation ; (5.) Results not 

 vitiated by aerial currents. 



* The presence of iron in an organic form in blood plasma was described by the 

 author in the Arris and Grale Lectures, delivered before the Rojal College of Surgeons 

 in 1886. Pamphlet, 1886. 



