CHAP. II.] THE BLOOD. 73 



folded or creased appearance like art ill-fitting glove. It cannot be denied 

 that these appearances are, at first sight, strikingly suggestive of a mem- 

 branous envelope ; but how little they prove the existence of such an 

 envelope the reader will find in Briicke's criticism of the question, too 

 long to be reproduced or even epitomized in this place 1 . With this under- 

 mining of the main support of the vesicular theory, its essential weakness 

 became evident. In the first place it is almost inconceivable that a fluid- 

 filled vesicle with walls which may collapse, should maintain the shape 

 of a biconcave or biconvex disk. In the second place, notwithstanding 

 the frequency of the search, no one has yet detected a structure at all 

 resembling the empty husk or skin of a red blood corpuscle. Indeed, 

 by alternately freezing and thawing blood, the coloured contents may be 

 extracted from blood corpuscles, leaving a colourless structure often exactly 

 resembling in shape and elastic property its red original. Of similar 

 import is the observation that the red corpuscles of amphibia may be cut 

 with a fine razor without the escape of any coloured contents 2 ; as well 

 as the observations that the corpuscles may be eviscerated of their nuclei, 

 becoming non-nucleated, but still coloured, spheroids; and that two coloured 

 cells may actually become fused into one 3 . When to these considerations 

 we add that no one has ever observed a double contour around the red 

 blood cells, even when they are swollen and spherical under the influence 

 of water, and that the attention of Schwann himself was arrested by its 

 absence 4 , we may acknowledge how very doubtful the alleged membrane 

 of red blood cells has always been. 



Most observers who adopted the view of the vesicular nature of red 

 blood corpuscles believed that the envelope included the coloured contents. 

 But the membrane was acknowledged to be slightly tinted red by Schwann 5 , 

 who remarked that, were it not so, the biconcave centre of the red cell 

 of man would appear colourless. On the other hand Prevost and Dumas 6 , 

 who succeeded in rupturing the corpuscles so as to permit the escape of 

 the nucleus, advanced the opinion that the colouring matter was not in 

 the contents, but in the skin. 



While, however, the prevailing idea of the red cell was that of a vesicle, 

 there were not wanting other ideas of it which approached the modern 

 one. Blumenbach 7 , in 1797, taught that the globules were small semi-solid 

 or gelatinous, lenticular masses, as did also de Blainville 8 ; and, later, 

 Donne 9 adopted a similar view. 



1 E. Briicke, "Die Elementarorganismen." Sitzungsber. d. k. Akad. Wien,Vol. 

 XLIV. Abth. ii. p. 387. 



2 Krause, Menschliche Anatomie, 1876. 3rd edit. Vol. i. p. 328. 



3 Article "Blood," by Bollett in Strieker's Handbook. Syd. Soc. Trans. Vol. i. 

 p. 391. 



4 Schwann, loc. cit. p. 69. 



5 Loc. cit. 



6 Prevost and Dumas, " Examen du sang et de son action dans les divers phe'no- 

 menes de la vie." Biblioth. univer. de Geneve, xvn. pi. in. fig. 3. Milne-Edwards, 

 Legons, Vol. i. p. 67. 



7 Blumenbach, Institutions physiologiques, traduit par Paget, 1797, p. 9. Milne- 

 Edwards, Legons, Vol. i. p. 67. 



8 de Blainville, Cours de phijsiologie, i. p. 214. Milne-Edwards, Legons, Vol. i. 

 p. 67. 



9 Donne, These sur les globules du sang, 1831, p. 13. Milne-Edwards, Legons, 

 Vol. i. p. 67. 



