Franklin P. Mall 320 
or else reticulum and eyen white fibers will take on some of the color 
and make them look like elastic fibers. H6hl has shown, however, that 
the reticulum fibers of the lymphatic gland, and even those of the 
spleen pulp, are accompanied in part by elastic fibers, a result which 
has been confirmed by Thomé™ and by myself.” I found that the amount 
of elastic tissue accompanying the reticulum in lymph nodes varied very 
much indeed and that often the periphery of the follicle contained many 
elastic fibrils while the centre had no fibrils at all that would stain with 
Weigert’s stain. This result corresponds well with that of Thomé. In 
the Malpighian follicle, however, the elastic fibers radiate from the 
artery and do not extend to the surrounding pulp. 
It is apparent from the above that the fibrils around the veins are 
mostly reticulum, and that elastic fibrils may accompany them. The 
work of Hoyer, Thomé and myself points clearly towards this conclu- 
sion. 
A discussion of the homogeneous elastic membrane of v. Ebner be- 
tween the fibrils encircling the veins and the large spindle-shaped endo- 
thelial cells within is more difficult. If this membrane is present it is 
an additional argument in favor of closed circulation through the pulp 
and is much in the way of both Weidenreich and Helly in their discus- 
sions. Weidenreich finds the membrane present but accepts an open 
circulation, while Helly, who believes in a closed circulation, sees foreign 
blood corpuscles and leucocytes passing through it. According to 
Bohm ~ these veins have an elastic intima analogous to that of the artery. 
Von Schumacher found it inconstant in man and absent in the dog. 
Hoyer was unable to find it at all. Furthermore, in an extensive study 
upon the elastic tissue of the spleen by Lebrell,* no mention is made of 
this elastic membrane. Were it present he certainly should have seen 
it. Since it is not supposed to be present in the dog’s spleen, my failure 
to find it is not remarkable, and from my experience with the Weigert 
elastic-tissue stain I am inclined to think that it really does not exist 
at all.” No doubt all stages of the development of reticulum, from the 
connective-tissue syneytium to the complete reticulum fibril with its 
accompanying elastic fiber, is found in the lymph follicle, judging by 
my own experience and by the works of Hoyer and Thomé. Recently 
Flint * has followed the development of the basement membranes in the 
19 Thomé, Jena. Zeit.. XX XVII, 1902. 
20 Mall, Amer. Jour. Anat., I, 1902, p. 361. 
21 BOhm, Von Kupffer Festschrift, 1899. 
2 Lebrell, Internat. Monatschr. f. Anat. u. Physiol., XX, 1903. 
23See also Kyber, Arch. f. mik. Anat., VI, 1870, p. 566. 
24Flint, Amer. Jour. Anat., II, 1902. ; 
