416 ' MANUAL OF HISTOLOGY. 



kidneys, exhibit a similar connection between the vessels of the paren- 

 chyma and capsule. 



For the recognition of the course of the lymph, also, we require the aid 

 of artificial injection. This may be successfully performed through the vas 

 afferens, though not easily. On the other hand, it may be very easily 

 effected by Hyrtl's method of puncture beneath the capsule. The true 

 course of the lymph through the gland was, however, first ascertained by 

 myself in the year 1860, and shortly afterwards by His. 



The afferent lymphatic, vessels (fig. 408, /, /) enter the organ either 

 singly or, as is the case with larger nodes, in greater number. Their walls 

 are thin, and they exhibit considerable variety of diameter and richness 

 in valves. There may also be one or several efferent vessels leaving the 

 glands. They have a similar structure to the last. 



Their point of exit may be a depression like the hilus, although not 

 necessarily, so that the distinguishing of afferent and efferent vessels from 

 one another is not always an easy matter. 



If we cautiously force in some injecting fluid through one of the vessels 

 leading into the organ, the first portion to nil is a series of spaces under 

 the capsule, closely communicating with one another, and surrounding 

 the follicle : this is effected with great ease. Perpendicular sections show 

 that the fluid penetrates also into the interior by keeping along the sides 

 of the follicles, and in the middle of the stream the banded network of 

 the interfollicular septa is seen distinctly. 



What is here produced artificially is effected by nature also. A few 

 hours after a meal of fatty food, the cortical portion of the mesenteric 

 glands is filled by white chyle in a manner precisely similar. 



It requires but a slight acquaintance with the lymph-nodes to convince 

 one's self that the injection fluid, in fact, on first entering the organ, 

 finds its way into the investing spaces of the follicle, and, filling these, 

 occupies those circular networks on the surface of the latter which have 

 been already mentioned above as being 0'0162-0 > 0323-0 1 04S3 mm. in 

 breadth. 



Close inspection shows farther that the afferent lymphatic vessel, 

 from that point at which it enters the capsule, loses its independent 



wall by the fusion of the 

 outer layers of the latter 

 with the connective-tissue 

 of the capsule. In this way 

 it opens into the investing 

 space, either in the form of 

 a simple or branched pas- 

 sage. Thus the effects of 

 injection are easily ex- 

 plained. 



It may be mentioned, as 

 a modification of this ar- 

 rangement, that the afferent 



Fig 408 lymphatic tubes sometimes 



first pass for a certain dis- 

 tance through the interfollicular partitions before opening into the lym- 

 phatic spaces of the gland. 



Let us bear in mind farther that the investing spaces of the organ 

 are immediately continuous with the network of interstices of the medul- 



