84 STRUCTURE OF COLORED BLOOD-CORPUSCLES. 



which can be made visible by the action of re-agents by depriving the cor- 

 puscle of coloring matter, and which, when it does not become visible, has 

 been destroyed by the re-agent." * According to Bottcher, the outer layer of 

 the same blood-corpuscle is not the same at all times and under all circum- 

 stances. He seems to regard the appearance of a distinct membrane as an 

 artificial production; but considers "the cortical layer as the result of a 

 process of development which deprives the blood-cells more and more of 

 their protoplasm, and finally converts them into homogeneous bodies." He, 

 therefore, classes it "with the capsule of cartilage cells, and with the cellu- 

 lose membrane of 'vegetable cells, "t Fuchs observed a membrane of a 

 certain power of resistance in frogs 7 red blood-corpuscles after keeping them 

 a few days on the slide without addition of any re-agent, which membrane was 

 particularly obvious when the nucleus made its exit out of the corpuscular 

 mass. t According to A. Bechamp, and J. Bechamp and Baltus, || the red 

 blood-corpuscles of mammals, birds, and amphibia possess a distinct mem- 

 brane, which can be thickened by adding a solution of starch to the blood, 

 and then becomes more resistant to the action of water. 



It has even been supposed that blood-corpuscles had more than a single 

 membrane; thus Roberts said^F his observations had led him "to the belief 

 that the envelope of the vertebrate blood-disk is a duplicate membrane ; in 

 other words, that within the outer covering there exists an interior vesicle 

 which incloses the colored contents, and in the ovipara, the nucleus." 

 Bottcher has refuted this notion, ** and it is characterized by Wedl, too, as 

 incorrect ; according to Wedl, when the cortical layer becomes swelled and 

 condensed, the double contour which is seen indicates its thickness but he 

 is "quite certain that whether it be called membrane or not, it is not simply 

 an artificial product." tt Lankester, in his conclusions regarding the verte- 

 brate red blood-corpuscle, says : "Its surface is differentiated somewhat 

 from the underlying material, and forms a pellicle or membrane of great 

 tenuity, not distinguishable with the highest powers (whilst the corpuscle is 

 normal and living), and having no pronounced inner limitation." tt Ranvier 

 thinks that the double contour the effect of dilute alcohol "proves the 

 existence, if not of a membrane, at least of a differentiated cortical layer. " 



Schmidt |||| calls attention to the double contour as being "the only proof 



* i bid., p. 480. 



t Compare " Neue Untersuchungen iiber die rothen Blutkorperchen." Memoires de 

 1' Academic Imperials des Sciences de St. Petersbourg, vii. Serie, t. xxii. (1876), No. 11, 

 p. 8 ; and the " Untersnchungen " in Virchow's Archiv, vol. xxxvi. (1866), pp. 357, 383, 

 387-9, and 404, with Archiv fur Mikroskopische Anatomie, vol. xiv. (1877), p. 93, or 

 "On the Minute Structural Relations of the Red Blood-corpuscles " (translated from the 

 preceding in), Quarterly Journal of Microscopical Science, October, 1877, p. 392. 



\ " Beitrag zur Kenntniss des Froschblutes," etc., 1. c., p. 91. 



"Recherches sur la Constitution Physique du Globule Sanguin." Compt. Rendus, 

 t. Ixxxv. (1878), No. 16, pp. 712-715. 



|| " Sur la structure du Globule Sanguin, et la resistance de son envelioppe h 1'action de 

 1'eau." IUd., No. 17, p. 761. 



IT e. 



** Op. cit. Virchow's Archiv, vol. xxxvi. (1866), pp. 392-395. 



tt L. c., p. 408. 



t* L. c., p. 386. 



" De 1'Emploi d'Alcool Dilu6 en Histologie." Archiv de Physique, 1874, pp. 790-793. 

 And again, " Recherches sur les Elements du Sang." Id., 2 Serie, vol. ii. (1875), pp. 1-15. 



III! "The Structure of the Colored Blood-corpuscles of Amphiuma tridactylum, the Frog, 

 and Man." Journal of the Royal Microscopical Society ; containing its Transactions and 



