208 DR. MARTIN BARRY ON THE CORPUSCLES OF THE BLOOD. 



by Schwann-}-, who examined nearly every animal tissue, and to those of Schleiden;}:, 

 whose observations have been so extended on the cells of plants. I think, indeed, 

 that many of the figures of Schwann afford evidence of the division in question 

 having taken place. It is to be recognized in his delineations of the cells of carti- 

 lage §, cellular tissue ||, the middle coat of the aorta ^, muscle-}^, tendon :j:J, the 

 feather §§, &c. The same remark is applicable to a figure given by Reichert of cili- 

 ated epithelium- cells II ||. Dr. Henle found that in the layers of his "Pflasterepi- 

 thelium" cells, the nucleus, very distinct in the lower cells, had almost disappeared 

 in those situated at the upper part. From this observation, and from the presence 

 of two nucleoli in some of the nuclei figured by this observer^^, as well as from 

 the nucleus becoming " more granular-f^-j-," I think it extremely probable that these 

 cells also (including those of the epidermis) are reproduced by the process just re- 

 ferred to — division of the nucleus ; additions being no doubt continually made at the 

 lower part of the layer, by which cells previously there are pushed further out. Dr. 

 Henle mentions that in the lowest of the cells of " Pflasterepithelium," the nucleus 

 is "reddish yellow, and has a remote resemblance to blood-corpuscles :|:JJ." This is 

 very interesting in connection with an observation recorded in my former paper on 

 the Corpuscles of the Blood. I stated that epithelium- cells had often presented ap- 

 pearances which almost suggested the idea that these too were changed corpuscles 

 of the blood : and that it was not easy to draw a line, by which the two could be 

 distinguished, either in colour, form, or general appearance §§§. The cells here re- 

 ferred to were probably the "cylinder," or rather the subsequently "flimmerepithe- 

 lium" cells of Henle llllll. 



78. I showed on a former occasion that the chorion arises by a coalescence of mi- 

 nute cells^^^; and we have since seen the thickening of this membrane to be 

 effected by the same means-f-f-J-'f'. The cell which (in the first of my communica- 

 tions to the Society) I called the ovisac, appears to arise in the same manner, as well 

 as the membrane e of my papers on the Embryo, for it really does appear, as I 

 formerly suggested JJJ J, that the substance surrounding the germinal vesicle in the 

 mammiferous ovum, usually called the yelk, may be termed a great " cytoblast." 



\ L.c. X L. c. § L. c, Tab. L figs. 8, 9. Tab. III. fig. 1. || Ibid. Tab. III. figs. 6. 9. 



% Ibid. Tab. III. fig. 12. tt Ibid. Tab. III. fig. 13. XX Ibid. Tab. III. fig. 11. 



§§ Ibid. Tab. II. fig. 11 a. \\\\ L. c. Tab. I. fig. 4. f f L. c. Tab. I. 



ttt Ibid. p. 7. XtX L. c, p. 6. §§§ L. c. par. 49. Plate XXIX. figs. 11, 12. 



llllll See my Researches in Embryology, Third Series, /. c, Plate XXVIII. fig. 251, which presents appa- 

 rently more advanced stages of the objects delineated in the figures referred to in the preceding note. 



%%^ Derived from corpuscles of the blood. Researches in Embryology, Third Series, l. c, par. 369-373. 

 On the Corpuscles of the Blood, /. c, par. 20-26. 



tttt Supplementary Note to a paper entitled " Researches in Embryology. Third Series : A Contribution 

 to the Physiology of Cells," in the present volume, p. 193. 



XXXX Third Series, /. c, par. 350. Note. 



