'50 Th. Lewis, 



XIV. Summary of chief Conclusions. 



The following' points are either new, or have not yet been suf- 

 ficiently emphasised by previous observers. 



1. It is probable that in addition to the spleen, glands which 

 may be placed in the category of ^liœmal" or ''''liamtal hjmjihatic" are 

 universally present in Mammalia. Comparable structures occur also 

 in Aves and Pisces. In Mammalia there is a definite distribution of 

 the different varieties of htiemolymph glands throughout the several 

 natural orders examined. Thus typical hsemal glands appear to be 

 restricted to the Primates and Ungulata, while in Carnivora haemal 

 lymphatic glands only are present. 



2. The haemal and h£emal lymphatic glands are distributed with 

 considerable degree of constancy in three main groups, renal, splenic 

 and suhvertebral. 



3. The blood or blood lymph spaces of these glands are traversed 

 by a fibrous reticulum, forming a network of spaces lined by cells 

 commonly called "reticulum cells", which form a continuous layer with 

 the typical endothelial cells bounding the sinus, and lining the vessels 

 entering or leaving it. 



4. In the modified hsemal glands of the rat, small arteries open 

 directly into the sinuses, while veins proceed from the sinuses and 

 appear to have direct communication with them, being strongly guar- 

 ded by valves. 



5. The glands in the rat and dog have been observed to have 

 an abundant nervous supply from the sympathetic. Stimulation of 

 the nerves, or gland itself, causes slight but definite paling of the 

 organ, and a diminution in size. 



6. In the liœmal lymphatic glands, the blood and lymph streams 

 meet, and to a great extent mix.^) 



7. Hœmal glands, inclusive of spleen, and hsemal lymphatic glands 

 are centres for the destruction of the blood elements both red and 



^) This may account for the abundant presence of blood in the lymph, 

 flowing from the thoracic duct, in cases where the inferior vena cava has been 

 clamped with the object of raising the blood pressure in the abdominal capil- 

 laries. (Starling, Schäfer's Text Book of Physiology. 1901.) 



