THE LEUCOCYTES IN ORGANIC FUNCTIONS. 727 



contains lymph supplied with myelin-granules, what is the dif- 

 ference between a nerve thus supplied with its primary source 

 of energy and a "medullated" nerve? None, it seems to us. 

 Such a nerve as a non-medullated nerve does not exist, therefore; 

 since a nerve deprived of myelin, if interpreted from our stand- 

 point, would become a mere plasma-channel. 



The pathway to all nerves becomes greatly simplified down 

 to their terminal ramifications, it seems to us, in the presence 

 of Gulland's observation concerning the passage of a basophile 

 leucocyte "through a narrow hole between two bundles of con- 

 nective tissue." Indeed "the lymphatic vessels do not exist as 

 distinct channels in the interfascicular connective tissue," says 

 Berdal. "There is no lymphatic vessel in the thickness of the 

 nervous bundles nor in the sheath surrounding them (Ran- 

 vier). The circulation of the lymph, in the interior of the 

 bundles, is insured by the arrangement of the interfascicular 

 connective tissue, the meshes of which represent lymphatic 

 cavities communicating with the vessels of the interfascicular 

 tissue through holes in the lamellar sheaths." On the whole, 

 therefore, it seems to us permissible to conclude that: 



1. The physiological function of the basophile leucocyte is to 

 convert fats derived from the intestinal foodstuffs into myelin- 

 granules, and to distribute the latter to all parts of the nervous 

 system, including the brain. 



2. The basophile leucocytes thus supply the entire nervous sys- 

 tem with the lecithin-containing compound which combines with the 

 oxidizing substance of the blood-plasma of axis-cylinders, neuroglia 

 fibrils, etc., in the production of nervous energy. 



LEUCOCYTES AND THEIR RELATIONS TO VITAL AND FUNC- 

 TIONAL PROCESSES. The varieties of leucocytes reviewed rep- 

 resent, it seems to us, the only three adult functional types, 

 the lymphocytes and hyalines being, as stated, immature cells. 

 This does not mean, however, that the latter are functionless; 

 indeed, we have seen that when an active process is initiated 

 these younger cells rapidly increase in the blood and intestinal 

 tract to replace the large number of their elders that have dis- 

 appeared to take part in this process. Their development must 

 be extremely rapid, therefore, and their number commensurate 

 with the number of adult leucocytes brought into action, 



