ON THE STRUCTURE OF THE MALPIGHIAN BODIES 297 



the line of junction, a somewhat more condensed tissue, which breaks 

 up, Hke a great deal of the red pulp, into spindle-shaped bodies, and 

 those fibres with onesided endoplasts, described by Kolliker, may be 

 found ; but this tissue belongs as much to the red pulp as to the 

 Malpighian body. 



In the Sheep, on the other hand, I find, to quote Mr. Wharton 

 Jones's words, that — 



" Examined with a low magnifying power, the Malpighian cor- 

 vesicles present the appearance of thick-walled, glandular vesicles, 

 with contents. The thick walls are not defined and homogeneous, 

 but are, on examination with a high power, found to be composed 

 of nucleated fibres and nucleated corpuscles, similar to those of the 

 red pulpy substance, between which, indeed, and the exterior surface 

 ■of the Malpighian corpuscles there is no very distinct line of demarca- 

 tion other than is produced by the condensation of the wall of the 

 Malpighian corpuscles and the absence in them of coloration." 



In addition to this, however, I find upon the exterior of the 

 Malpighian bodies in the Sheep the mesh-work of pale fibres (fig. 2, 

 d'), like very young elastic tissue, or the fibres of the zonule of zinn, 

 to which Kolliker and Sanders have referred ; and I have occasionally 

 met with such fibres in the interior of the bodies themselves, travers- 

 ing the Malpighian pulp. They appear to me to belong to the 

 original tunica adventitia of the arteries. The existence of any distinct 

 structureless limitary membrane may, I think, be very decidedly 

 denied ; and with regard to the " granular membrane, the internal 

 surface of which is lined by a layer of large nucleated cells, while free 

 nuclei or corpuscles, with a homogeneous or granular plasma, fill its 

 interior'' (Sanders, 1. c, p. 35); all I can say is, that I cannot give 

 any opinion as to what it may be, never having met with a Malpighian 

 body presenting any such structures. 



It may be said, then, that the Malpighian bodies of the mammalian 

 spleen are not closed follicles, and have no analogy whatever to the 

 acini of ordinary glands, but that they are portions of the spleen, 

 everywhere continuous with the rest, but distinguished from it — a, by 

 immediately surrounding, and as it were replacing, the tunica adventitia 

 of the arteries ; b, by containing no wide venous sinuses, but, at most, 

 a network of delicate capillaries ; and c, by being composed of abso- 

 lutely indifferent tissue, i.e., of a structureless periplast with imbedded 

 endoplasts — or of a tissue in which the periplast has undergone no 

 further metamorphosis than that into cell-wall and rudimentary fibre. 



For a demonstration that each of these propositions holds good of 

 the Malpighian bodies in the other three classes of the Vertebrata, I 



