456 OF ABSORPTION AND SANGUIFICATION. 



481. Ductless Glands. There is reason to believe that a similar office is per- 

 formed by certain bodies connected with the Circulating system, which possess 

 the essential elements of the Glandular structure, without any efferent ducts ; 

 these must restore to the circulating current any substances which they may 

 withdraw from it; and there seems adequate ground, therefore, for the conclu- 

 sion, that their action, whatever it may be, is subsidiary to the completion of 

 the process of Sanguification being exercised, perhaps, upon that portion of 

 the nutrient materials more especially, which did not traverse the Absorbent 

 system when first introduced, but which was directly taken up by the blood- 

 vessels. The organs in question, which have received the distinctive appellation 

 of Vascular or Ductless Glands, are the Spleen, the Thymus, Thyroid, and Supra- 

 renal bodies. Of these, the Spleen deserves especial notice, on account of its 

 size and obvious functional importance in the adult ; the others appear to minis- 

 ter more particularly to the requirements of the system at the earlier periods of 

 life. 



482. The minute- structure of the Spleen has recently been made the subject 

 of careful research by many excellent Microscopic observers ; and more espe- 

 cially Prof. Kb'lliker 1 and by Dr. Sanders. 3 The following is a summary of the 

 most important points which they may be considered to have determined. 



I. The fibrous coat in Man is composed of white fibrous tissue, with an inter- 

 mixture of yellow or elastic fibres; in many of the lower animals, however, it 

 contains non-striated muscular fibres composed of fusiform fibre-cells. 



II. The trabecular tissue consists of fibrous bands, and threads which arise 

 from the inner surface of the fibrous envelop, and form a network that extends 

 through the entire organ, becoming connected also with the fibrous sheaths of 

 the vessels which penetrate it. These bands are partly muscular in the animals 

 which have muscular fibres in the external envelop of the spleen; but elsewhere 

 they are simply fibrous. The spaces left by their intersection, which are by no 

 means regular either as to form or size, are occupied by the splenic corpuscles 

 and splenic parenchyma. In the trabeculae of the human spleen, Prof. K. has 

 discovered some peculiar fusiform cells with round nuclei, which are probably to 

 be considered as contractile cells not developed into their properly characteristic 

 form ( 305). 



in. The peculiar Splenic Corpuscles, sometimes termed the " Malpighian cor- 

 puscles" of the Spleen, are whitish spherical bodies, which are imbedded in the 

 splenic parenchyma, but are connected with the smaller arteries by short pedun- 

 cles, like grapes with their fruit-stalks, or are sessile upon their sheaths. Owing 

 to the rapid changes which they undergo after death, and the influence of pre- 

 vious disease and abstinence, they are seldom seen in the Human subject, but 

 are best seen in the perfectly fresh spleens of the Ruminantia ; there is no doubt, 

 however, of their invariable presence in the healthy human subject, although 

 this has been denied by many anatomists. The size of these corpuscles, when 

 fully developed, varies from about l-3d to l-6th of a line; smaller bodies, how- 

 ever, are met with, which appear to be Malpighian corpuscles in an earlier stage 

 of evolution. Each of them consists of a delicate fibrous envelop, derived from 

 the sheath of the artery to which it is attached, and frequently surrounded by 

 capillaries of extreme minuteness. It contains, as its constant and essential 

 elements, nucleated cells of from l-6000th to l-4000th of an inch in diameter, 

 pale and faintly granular, together with free nuclei (the proportion of which to 

 that of the fully-formed cells is extremely variable), and a few of larger size, 

 and more distinctly granular before the addition of reagents, from 1-3 500th to 



1 "Cyclopaedia of Anatomy and Physiology," Art. "Spleen;" and " Mikroskopische 

 Anatomic," band ii. gg 183 189. 



2 "Annals of Anatomy and Physiology," No. 1. 



