74 SCIENCE PROGRESS 



10. Morphology of Blood-coagulation 



Recent papers of Loeb on the process of coagulation in 

 vertebrate blood, those of Ducchesi, Burker, and more recently 

 Nolf, deal with this part of the subject. Loeb, whose view 

 corresponds in some respects to that of Nolf, who worked with 

 the blood of vertebrates, distinguishes two distinct phases in 

 coagulation : 



i. The stage of agglutination of leucocytes in arthropoda 

 and Crustacea, and of blood-platelets in mammals. 



2. The formation of fibrin from this agglutinated stage. 



Loeb finds that peptone does not hinder clotting in the lobster, 

 neither does kinase from vertebrates induce coagulation in the 

 blood of invertebrates. In the blood of Limulus he states that 

 a fibrinogen coagulable at 56 does not exist, and that this tem- 

 perature does not interfere in any way with the first stage of 

 coagulation. On dilution with water the blood of this animal 

 shows agglutination of leucocytes, and the remaining liquid clots 

 easily on the addition of muscle-extract from the same animal. 



The macroscopic appearances on glass in shed blood to which 

 Ducchesi 1 has drawn attention as the first alteration which 

 blood undergoes outside the body, is due to an accumulation of 

 platelets, and is a phenomenon entirely absent in peptone or 

 hirudin-blood. This is also a definite agglutination process. 

 Every observer, however, has seen that the bodies termed 

 " platelets " are preserved in both these fluids. But agglutina- 

 tion rarely occurs. Regarded purely from the morphological 

 point of view, it is possible that both inside and outside the 

 body any damage to the blood-plasma is followed firstly by 

 production and secondly by agglutination of previously non- 

 existent platelets, 2 and then this stage is succeeded by the 

 subsequent appearance of fibrin. As far as the relation of these 

 phases to the coagulation process is concerned, this view is 

 similar to that recently proposed by Burker. 



1 Hofmeister's Beitriige t iii. p. 378. 



2 I am able to confirm a recent observation of Marino (Comfttes rend. No. 4, 

 1905), who observed that when rabbits' blood is received into so much absolute 

 alcohol that this is only slightly diluted, no platelets can be demonstrated to 

 exist. It is inconceivable that they are destroyed, since the same blood mixed 

 with 95 per cent, alcohol yields an abundant supply. This experiment, therefore, 

 lends no support to the view that platelets exist in undamaged circulating blood. 



