THE HISTOLOGY OF THE BLOOD OF LARVA OF LEPIDOSIREN PARADOXA. 467 
Series 113C. 24. x 700. Below and to right is pronephric duct (P.D.) The sinus is crossed by delicate 
protoplasmic strands with elongated nuclei. In the meshes of this reticulum, polymorphonuclear granular 
leucocytes (yp.). In sinus space itself many large mononuclear cells, also erythrocytes drawn in outline, 
some of them in division. 
Fig. 26. Section through mesonephros. Stage 32+, Series 113C. 40. x 500. A, aorta; C.V., 
cardinal vein; P.D, pronephric duct. The nuclei of the tubules have not been filled in. The meshes of 
the reticular tissue are filled with leucocytes of all varieties. 
Fig. 27. Section through splenic vein. Stage 36, Series 139. 19. x 300. a, outline of stomach 
wall; }, spleen; e, liver. In vein, a polymorphonuclear leucocyte and four mononuclear cells. 
Puate LV. 
Fig. 28. Section through spleen rudiment. Stage 32+, Series 113C. 22. x 400. Below and to 
right, outline wall of stomach. 
Fig. 29. Section through spleen rudiment. Stage 33, Series 108.11. x 300. Below and to night, 
wall of stomach, with its nuclei represented in outline. a, a, a, peripheral blood sinus, 
Fig. 30. Section of spleen ; Stage 37; Series 139. 20. x 200. 5S, outline wall of stomach. 
Fig. 31. High-power view of portion of same section, showing cellular trabecule and spaces containing 
red blood corpuscles and white cells of different varieties. x 700. 
Fig. 32. Section of anterior end of spleen. Stage 39, Series 137B. 11. x 400. Above and to 
left, vein (spv.) ; in centre of spleen, artery (a). 
Fig. 33. Portion of same. x 850. a, central artery; 0, peripheral sinus, Four large cells in a row : 
to left, two large mononuclear spleen cells, ¢; to right, secondary erythroblast with hemoglobin, d; in 
centre, primary erythroblast, e. Cells f and g were introduced from a neighbouring section ; f has a nucleus 
like the spleen cells, c, but the basophile protoplasm shows delicate concentric fibrillation; g has a similar 
but deeply notched nucleus, and the protoplasm is very delicate and hyaline. It is probably a leucoblast. 
TRANS, ROY. SOC. EDIN., VOL. XLI, PART II. (NO. 18) 60 
