RECENT LITERATURE. 221 



Chemically also, as has been shown by Halliburton and Friend, the red corpuscles lack 

 substances, such as cell-albumin and nucleo -albumin, which are characteristic of 

 typical animal cells. They contain, however, a small amount of cell-globulin, and this 

 appears to be their only proteid. Further, although originally formed from and within 

 protoplasm (see above, Intracellular development, and Development in marrow), they 

 have lost all amoeboid properties in fact, as the study of their formation within the 

 angioblasts shows, the protoplasm from which they are formed becomes trans- 

 formed into little but a solution of haemoglobin, which as their development 

 proceeds, becomes confined by a delicate pellicle of " stroma substance." This may 

 itself be a deposit formed around the hasmoglobin-globules by the cell-protoplasm, 

 or may be a modified remainder of that protoplasm which is left around the globule. 

 On the other hand, the nucleated red corpuscle of oviparous vertebrates, although 

 its general structure and mode of development show it to be morphologically a cell, 

 yet has in the adult none of the functional characteristics of cells. Nor so far as we 

 know is it in the adult condition capable of undergoing division and multiplication, 

 although the nucleus retains the structure and chemical composition which is typical 

 of cell-nuclei. The cell-body, on the other hand, has both histologically and chemi- 

 cally lost the properties of cell-protoplasm, and as in the case of the mammalian 

 corpuscle is wholly transformed into a homogeneous mass or solution of haemoglobin 

 with a delicate enclosing pellicle. Some authors have, it is true, described a reticular 

 structure within these corpuscles, but there is little doubt that such reticulum has 

 been artificially produced by the reagents used to fix the corpuscles. These nucleated 

 corpuscles of ovipara differ from the nucleated corpuscles of the mammalian 

 embryo, for the latter are true functional cells, capable of division, and exhibiting 

 amoeboid phenomena, and in short differing from a typical animal cell, such 

 ns the white corpuscle, only in the presence of haemoglobin in their protoplasm. The 

 nucleated coloured cells of the marrow are in all respects similar to them. 



Historical. The development of blood-corpuscles in isolated patches in the vascular area 

 of the chick was first recognised by Pander, who termed the patches " blood-islands." Remak, 

 and after him, His and Kolliker, described the first vessels in the vascular area of the chick as 

 originating in the form of a solid cord of mesoblastic cells, arranged so as to form a network ; 

 the peripheral cells of the vascular cords becoming flattened and forming- the epithelium of the 

 vessels, whilst the centrally placed cells become directly converted into blood- corpuscles, acquiring 

 colour first of all at certain points the blood-islands of Pander and fluid accumulating 

 between them to form the liquor sanguinis. His stated, moreover, that the blood-vessels 

 within the body of the embryo originate as ingrowths from these vessels of the vascular area. 1 

 Strieker was the first to describe the formation of blood-vessels by the hollowing out of con- 

 nective tissue-cells, and Afanasieff and Klein proved that the blood-islands of Pander were 

 cells of the mesoblast, in the interior of which blood- corpuscles had made their appearance, 

 and that the containing cells became the first blood-vessels. Klein's account was confirmed, 

 and in some particulars modified, by Balfour. The account above given of the formation of 

 vessels and blood-corpuscles in the vascular area of mammals is derived from observations 

 upon the embryo of the guinea-pig. The production of red blood-disks in the interior of 

 certain cells of the connective tissue was first noticed by me in the subcutaneous connective 

 tissue of the new-born rat, and subsequently in the embryos of a number of different animals, 

 and these observations were confirmed by Ranvier who terms the connective tissue-cells con- 

 cerned in the process " vasoformative cells " as well as by Leboucq and others. The dis- 

 covery of the important fact that in the adult condition the main if not the only seat of 

 formation of red blood-corpuscles is the red marrow of the bones, is due to the researches of 

 Neumann, which were first published in 1868. 



RECENT LITERATURE. 



Auerbach, L., Die BlutTcorpercJicn dcr BatracMen, Anat. Anzeiger, 1890. 



Bizzozero, G-., Ueber die Entstehung der rotlien Blutkorperclien w'dhrend des Extrautcrinlebens, 

 Moleschott's Untersuch. zur Naturlehre, xiii, 1883 ; Ueber die Bildung der rotlien Blutkorperchen, 

 Virchow's Archiv, Bd. 95, 1884, Arch. f. raikr. Anat., Bd. xxxv. , 1890 ; NouveLles recherches s. la 

 structure de la moelle dcsos chez les oiseaux, Archives ital. de biologie, T. xiv., 1891. 



1 Tide Embryology, p. 25. 



Q 2 



