68 ENZYMES OR SOLUBLE FERMENTS. 



took this view, basing it on an elaborate series of investigations for 

 which his original works must be consulted 1 . Lb'wit experimenting 

 with lymph as well as blood, while denying that the white corpuscles 

 break down at clotting in the way Schmidt described, still connects 

 them with the production of the initiative factor in the whole process 2 . 

 Still further evidence in the same direction may be derived from the 

 experiments of Rauschenbach 3 and Halliburton 4 and of Fano, who 

 observed that when peptone-plasma is freed as completely as possible 

 from white corpuscles it cannot be made to clot in the usual way by 

 the addition of water 5 . 



In addition to the red and white corpuscles blood also contains, as already 

 described ( 33), a third structural element, the 'platelets,' and several observers 

 have endeavoured to connect the first cause of the clotting of blood with some 

 breaking down and disappearance of these structures 6 . This view is as yet in- 

 sufficiently supported, and is combated by several observers 7 ; bearing in mind 

 however how little is known about the origin and nature of these platelets the 

 question of their relationship to blood-clotting must still be regarded as awaiting a 

 decisive answer. 



In addition to the undoubted relationship of leucocytes to fibrin- 

 formation it appears that the protoplasm of many other cells, both 

 animal and vegetable, may exert an influence similar to that of the 

 white corpuscles of blood 8 . 



Wooldridge regarded the leucocytes as entirely secondary and very subordinate 

 factors in the process of clotting, as also the fibrin-ferment. According to his view 

 blood-plasma contains in itself all the elements requisite for the formation of fibrin, 

 which he considers to be in no sense the outcome of any fermentative process. He 

 described three coagulable proteids A- B- and C-fibrinogen. The last of these 

 occurs in minimal quantities in plasma, is identical with the substance ordinarily 

 known as fibrinogen, and clots on the addition of fibrin- ferment. According to his 

 view clotting is due to a transference of lecithin from its combination with A- 

 fibrinogen to .B-fibrinogen, by which means both the fibrinogens disappear and 

 fibrin takes their place 9 . 



1 PfiiigerWrcft. Bd. ix. (1874), S. 353; xi. (1875), Sn. 291, 515. 



2 .Sitzb. d. Wien. Akad. (2 Abth.), Bd. LXXXIX. (1884), S. 270; xc. S. 80. 



3 Inaug.-Diss. Dorpat, 1883. See also the Dissertations (Dorpat) of Hoffmann, 

 1881. Samson-Himmelstjerna, 1882 ; Heyl, 1882. 



4 loc. cit. See also Kruger, Zt. f. Blol. xxiv. (1888), S. 189. 



5 Arch.f. Physiol. Jahrg. 1881, S. 288. Centralb.f. d. med. Wiss. 1882, S. 210. 



6 Hayem, Gaz. med. de Paris, 1878, p. 107. Compt. Rend. T. LXXXVI. (1878), p. 

 58. Arch, de Physiol. 1878, p. 692. Bizzozero, Virchow's Arch. Bd. xc. (1882), S. 

 261. Laker, Sitzb. d. Wien. Akad. (2 Abth.), Bd. LXXXVI. (1883), S. 173. Hayem's 

 colourless ' haematoblasts ' are identical with Bizzozero's ' platelets.' The true 

 haematoblasts are the cells described by Neumann, Eindfleisch and others as 

 occurring in the red marrow of bones. 



7 Fano, Centralb. f. d. med. Wiss. 1882, S. 210. Lowit, loc. cit. Schimmelbusch, 

 Virchow's Arch. Bd. ci. (1885), S. 201. 



8 Rauschenbach, loc. cit. Grohmann, Inaug.-Diss. Dorpat, 1884. 



9 Croonian Lecture, Eoy. Soc. Lond. 1886. Ludwig's Festschrift, 1887. See 

 also Halliburton, loc. cit. antea. 



