366 THE THYMUS GLAND, BY E. KLEIN. 



united into fasciculi of various sizes, which decussate in all direc- 

 tions, and thus form a tolerably resistant membrane ; fine elastic 

 fibrils, which are partly united in a plexiform manner, and 

 partly form large arches running in an irregular manner between 

 the fibres of the connective tissue ; a few lustrous, broad, strongly 

 refracting bands, characterised by their looped course and 

 resistance to the action of acids ; and, lastly, cellular ele- 

 ments. These either resemble colourless blood corpuscles, or 

 are provided with processes like the so-called stellate cells, or 

 they may appear as large, finely granular, irregularly shaped 

 bodies, usually containing a single small, spheroidal, highly re- 

 fracting nucleus. On the outer surface of the capsule, or that 

 which is directed towards the thoracic cavity, a single layer of 

 pavement epithelium, resembling in form and character that of 

 the peritoneum, may easily be demonstrated. The cells of this 

 layer are polyhedral, and slightly elongated or rhombic in form, 

 containing a vesicular spheroidal or elliptical nucleus. 



If a portion of the capsule, carefully detached from the re- 

 cently removed thymus of a dog, be spread out upon the slide 

 with the aid of some indifferent fluid, and examined with a 

 high power, besides the tissues and structures above mentioned 

 we may discern also the deeply situated delicate ramifications 

 of the bloodvessels, together with the sparingly distributed 

 trunks of medullated nerve fibres ; and lastly, certain peculiar 

 cavities. At the points where two or more strong fasciculi of 

 connective tissue decussate we meet with such large usually 

 elongated spaces, which have somewhat sinuous margins 

 bounded by a single layer of fusiform disproportionately large 

 cells ; the tissue immediately external to these, and forming a 

 kind of wall to the cavity, is but little condensed. It is clear 

 that we have here to deal with the cavities belonging to the lym- 

 phatic system, respecting which it is difficult to state decisively 

 whether they are simple lymph sacs, or are wide thin-walled 

 lymphatic vessels. It is worthy of remark, that the quantity of 

 lymph corpuscles they contain is extremely small, and bears no 

 proportion to the size of the space. 



The tissue bounding the several follicles of the thymus, and 

 dipping into the interior of the organ from the surface of the 

 several lobules, consists of a network of connective tissue, 



