JOURNAL OF MICROSCOPICAL SCIENCE. 



DESCRIPTION OF PLATE X, 



Illustrating Prof. Lankester's observations on the Blood- 

 corpuscles (see p. 68), and Mr. D^Arcy Power's on the 

 Endothelia of the Common Earthworm [Lumbricus 

 terrestris) . 



Figs. 1 to 6 are from drawings by Mr. Lankester. 



Figs. 7, 8, and 9 are from drawings by Mr. D'Arcy Power. 



Fig. 1. — Small blood-vessel from testis of earthworm, treated with osmic 

 acid and subsequently stained with picrocarmine. x, The structureless 

 blood-clot, coloured naturally by haemoglobin ; n, nuclei of the wall ; c, 

 corpuscles (free nuclei). 



Fig. 2. — A similar blood-vessel of smaller calibre. 



Fig. 3. — Some of the free nuclei or blood-corpuscles drawn to a larger 

 scale. The actual short diameter of these corpuscles is yoVo^^ °^ ^^ inch. 



Fig. 4. — An Amoeboid corpuscle from the perivisceral fluid of the 

 earthworm, drawn from a specimen preserved by treatment with osmic 

 acid and picrocarmine. This corpuscle is represented on the same scale of 

 amplification as those given in fig. 3. 



Fig. 5. — Two vascular swellings or globules, from a capillary of a 

 segmental organ or " nephridium." A is represented as seen after silver- 

 treatment, showing the cell-outlines of the capillary and globule; B is 

 from a spirit-specimen stained with Kleinenberg's haematoxylin. The 

 centre of B is occupied by the corpuscles first noticed by Gegeubaur. 

 They appear to be somewhat smaller than those found in the vessels 

 elsewhere. 7i, Nuclei of the wall-cells forming the wall. 



Fig. 6. — Portion of a larger vessel from a muscular septum (osmic acid 

 and picrocarmine). «, Nuclei; c, corpuscles (free nuclei); t», inner coat 

 of the vessel ; ad, outer coat. 



Fig. 7. — Two blood-vessels from the side of a nephridium or segmental 

 tube : probably an arteriole and a venule. The outlines of the cells 

 constituting the vascular wall are rendered evident by silver-staining, and 

 are seen to difi'er markedly in the two vessels. The outlines are accurately 

 copied from the preparation, and consequently some of the divisions between 

 adjacent cells are not given, not having taken up the staining. 



Fig. 8. — Cell-outlines from silver-staining of a larger blood-vessel. 



Fig. 9. — Retiform tissue from the earthworm, closely similar to that of 

 the mammalian omentum. This tissue is found supporting the coils of the 

 successive nephridia or renal tubes. The cell outlines are brought into 

 view by silver-staining. 



Fig. 10. — Endothelial cell-outlines from the surface of retractor muscle 

 of Sipunculus nudus, stained with silver. From a drawing made by Mr. 

 Lankester in 1872. 



