( oy) 
XI.—The Histology of the Blood of the Larva of Lepidosiren paradoxa. Part I. 
Structure of the Resting and Dividing Corpuscles. By Thomas H. Bryce, 
M.A., M.D. (With Five Plates.) 
(Read January 18, 1904; MS. received March 19, 1904. Issued separately November 19, 1904.) 
The material for the observations recorded in this paper has been kindly lent to- 
me by Mr Granam Kerr, Professor of Zoology in the University of Glasgow. It 
consisted of some of his beautiful series of cut embryos, and of some freshly-sectioned 
material which I stained specially for the purposes of the research. 
The blood corpuscles of the embryo Lepidosiren are exceptionally favourable objects 
for the study not only of the morphology of the blood, but also of cell structure. The 
karyokinesis in the red corpuscles presents features of considerable interest—and the 
phenomena are presented to the observer on such a scale as to render them almost 
diagrammatic. 
In the present paper I shall deal with the structure of the corpuscles and the 
mitotic phases in the erythrocytes, reserving for a future communication the results of 
studies on the origin and histogenesis of the elements. 
MeETHops. 
For the study of the dividing red corpuscles I selected a stage in which the embryo 
was small enough to have permitted perfect penetration of the fixative fluids, and yet 
sufficiently advanced to have its cells free of yolk. 
The stage selected was that represented in pl. x. fig. 32 of Mr Granam Kerr’s 
memoir* on “The External Features in the Development of Lepidosiren paradoxa 
(Fitz.),” a larva twenty-four days after hatching. 
The embryos chosen had been fixed in sublimo-acetic fluid, and the fixation leaves 
nothing to be desired. 7 
The sections were cut at 10 «, which was rather thick for some points, but the 
nature of the material, owing to the mass of yolk, did not permit of thin sections. 
The stain employed was in the first instance iron hematoxylin, with a counter 
stain of eosin. It was, however, discovered that even at this early stage several 
varieties of leucocytes were present in the blood, and for the study of these a stain of 
methylene blue and eosin, and the mixture of Ehrlich known as Triacid were employed. 
The best results in some respects were obtained with the first named, especially for 
the centrosome of the erythrocytes, but for the resting red corpuscles and the leucocytes 
the methylene blue and eosin gave a finer differential colorisation. 
* Phul. Trans., vol. cxcii. B. 182, 1899. 
TRANS. ROY. SOC. EDIN., VOL. XLI. PART II. (NO. 11). 44 
