ELABORATION OF NUTRIENT MATERIALS PEYER's GLANDS. 207 



mania, 1 Frey, 2 aud v. Recklinghausen. 3 From their investigations we learn 

 that each gland is invested by a vascular sheath or capsule of condensed 

 connective tissue, which is continuous with the coats of the afferent and 

 efferent vessels, sending inwards a number of thin lamellre, so disposed aud 

 connected together as to constitute a tolerably regular alveolated framework 

 pervading the gland, excepting usually near the centre. The septa thus 

 formed contain, in Man and many other animals, but especially the Rumi- 



FIG. 84. 



A section of a simple Rete Mirabile, viewed from the surface, a, a, afferent vessels ; 6, b, efferent 

 vessels, only partially visible, from the popliteal space. (Man.) 



nants, numerous muscular fibre-cells, d, d, Fig. 85. The alveoli are most dis- 

 tinct near the surface of the gland, c, c, Fig. 85 ; towards the centre, in con- 

 sequence of the breaking up and irregular disposition of the septa, they are 

 not very apparent. The centre of the gland is occupied by the medullary 

 substance, varying considerably in amount in different instances, but always 

 most abundant in childhood, and in the more deeply-seated glands. Its re- 

 lation to the alveoli may best be understood by conceiving it to be a plastic 

 substance, accumulated in mass at the centre, and sending out on all sides 

 prolongations of the most irregular form and shape, which do nearly, but 

 not completely, fill the alveoli, spaces being consequently left between the 

 septa which form the alveoli, and the processes of medullary substance 

 partially filling them. These are termed by Frey the investing spaces of 

 the follicle, and are represented by b in Figs. 86 and 87. They are traversed 

 by irregular fibres, formed of nucleated cells with anastomosing prolonga- 

 tions, c, c, Fig. 87. According to v. Reckliughausen, 7 they are lined by epi- 

 thelial cells of a rounded polygonal form, and certainly contain numerous 

 lymph-corpuscles. They are directly continuous with the afferent and effer- 

 ent vessels, and may be filled with injection propelled from either of those 

 sets of tubes ; though, of course, on account of the valves, more readily 



1 Op. cit. 



2 Untersuch. Ub. die Lymph-driisen des Menschen, Leipzig, 1861. 



3 Strieker's Hum. and Comp. Hist., Syd. Soc. Trans., 1870. 



4 See also Bizzozero, Centralblatt, 1873, p. 110. 



