296 THE BLOODVESSELS, BY C. J. EBERTH. 



arteries. Their number and size is often so considerable that 

 true cavernous spaces are formed, and the intervening sub- 

 stance is reduced to a thin framework. 



Around these vessels, and immediately external to their 

 delicate cellular internal membrane, which is identical with that 

 of the ordinary capillaries, lie rounded and elongated heaps of 

 slightly polygonal cells, which are never invested by a definite 

 structureless membrane, but have only a layer of connective tissue 

 with longitudinal fibres on their outer surface. Many capillaries 

 are invested, and frequently for considerable tracts, with a 

 single layer of these cells, which are covered by a fibrous 

 tunica adventitia containing numerous nuclei. 



Small groups of similar cells lie also more remote from the 

 vessels in the matrix or intervening substance. The larger 

 cell masses must therefore be regarded as richer collections of 

 these scattered through cellular vascular sheaths. 



The size of these cell masses diminishes in proportion to the 

 development of the vascular sacculi. 



On one occasion I found in the cell masses laminated struc- 

 tures similar to those found in the granules of the thymus. 



The intervascular tissue of the coccygeal gland is very rich 

 in nerves. As regards the ganglion cells, which Luschka stated 

 he had observed, neither Arnold, Krause, nor myself have been 

 able to satisfy ourselves of their presence. Nor have I been 

 more fortunate in obtaining a view of the club-shaped termi- 

 nations of the nerves resembling Pacini's corpuscles, or terminal 

 bulbs, described by Luschka. They are said to be O8 milli- 

 meters broad, and to possess a thick membranous and fibrous 

 investing sheath containing numerous longitudinal nuclei. 



Inasmuch as a glandular structure is not demonstrable in 

 the so-called coccygeal gland, which rather appears to consist 

 of a rich plexus of for the most part capillary vessels, invested 

 by a cellular sheath, some of which are normal, whilst others 

 are dilated in a fusiform or sacciform manner, it is clear that 

 for the future it should be named the plexus vasculosus coccy- 

 geus, and that it should be classed with the carotidean vascular 

 plexus of the so-called carotid gland, at the upper extremity 

 of the common carotid of man and mammals. 





