No. I.] BLOOD CORPUSCLES. j^ 



3. Cells of smaller size, containing haemoglobin. The nu- 

 cleus, also, is smaller, and shows a reticular structure. The 

 next stage is the nucleated red corpuscle proper, which differs 

 from (3) in the deeper tint of the haemoglobin and the smaller 

 size of the nucleus. The nucleus is distinguished further 

 by the fact that it stains more deeply with hnematoxylin. 

 Malassez differs from other histologists in his explanation of 

 the way in which the ordinary non-nucleated red corpuscle 

 is derived from the nucleated form. According to him, the 

 latter do not lose their nuclei at all, but give rise to the ordi- 

 nary red corpuscles by a process of budding. The buds are 

 constricted off, and are first spherical, but afterward become 

 biconcave, partly from the mechanical action of the circulating 

 blood, partly because of an unequal diminution in bulk. Foa 

 and Salvioli (13) also derive the nucleated red corpuscle from 

 a colorless or " hyaline cell." This latter cell originates both 

 in the embryo and the adult from the large giant cells found 

 in the marrow during extra-uterine life, and in the liver and 

 the spleen of the foetus during the period when these organs 

 are producing red corpuscles. The giant cells, myeloplaques, 

 of Robin are of two kinds, at least, in the red marrow. One 

 variety is large, finely granular, and contains a number of oval 

 separate nuclei, which correspond to the myeloplaques as 

 usually described. The second variety is not multinucleated, 

 but has a very large coiled, or twisted, nucleus, made up, 

 apparently, of a number of smaller nuclei, which are, how- 

 ever, still in connection with one another. This variety 

 Bizzozero described as the "giant cell with budding nuclei " ; 

 and Foa and Salvioli believe that they give rise to the hya- 

 hne cells, from which the nucleated red corpuscles are after- 

 wards formed. They give to this kind of giant cell, therefore, 

 the name of h?ematoblast. The haematoblasts separate into 

 a number of smaller hyaline cells, the large nucleus breaking 

 up into separate "buds," each of which becomes the nucleus of 

 a hyaline cell. The hyaline cells change to nucleated red cor- 

 puscles by the development of haemoglobin within the cell sub- 

 stance ; and these latter pass to the non-nucleated form in 

 consequence either of an absorption or an extrusion of the 

 nucleus. In a later paper, Foa {22) expresses his belief that 

 the nucleus disappears within the cell by absorption. Osier 



