ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 29S 



b. Histolog-y. 



On the Process of Hair turning White. * — E. Metchnikoff finds 

 that this is due to the intervention of phagocytes of the hair. These 

 cells have a single nucleus and numerous amoeboid processes ; they are 

 derived from the medullary part of the hair, make their way out into its 

 cortical layer, absorb pigment-granules, and retire to the root. The 

 phagocytes become more and more scarce as the hair whitens, and most 

 frequently disappear entirely. Hair turning white in a single night, or 

 in a few days, may be explained as due to unusual activity on the part 

 of the phagocytes. This mechanism of the whitening of the hair through, 

 the agency of phagocytes allows this case of atrophy to be classed under 

 the general laws of atrophy of the solid parts of the organism. 



Accessory Lobes on Spinal Cord of Birds.f — P. Lachi refers to a 

 communication by von Kolliker, J on aggregates of nerve-cells on the 

 sides of the spinal cord in birds (Hofmann-Kolliker nuclei). In 1889 § 

 Lachi gave an account of the lumbar and sacral region of the spinal 

 cord in goose, fowl, pigeon, &c, aud stated the following conclusions. 



The lumbar swelling shows 5-8 pairs of metamerically disposed 

 " accessory lobes." These lobes consist of nerve-cells and of a gelatinous 

 stroma analogous to the gelatinous substance of the rhomboidal sinus. 

 They are derived from the anterior horns and become distinct about the 

 eighth day of incubation. They have counterparts in the accessory lobes 

 of some bony fishes (Ussow) and others observed in the alligator, and 

 they throw some light on somewhat similar aggregates of nerve-cells^ 

 recognised in the lumbar expansion in man. 



Nutritive Channels within the Liver-Cells communicating with 

 the Lobular Capillaries. ||— Prof. E. A. Schafer describes sections from 

 a rabbit's liver, injected with carmine-gelatin from the portal vein, which 

 show within the cytoplasm of the cells — but not within the nucleus — a. 

 network of fine varicose canaliculi filled with the red injection and com- 

 municating here and there directly with the lobular capillaries, which 

 are also completely injected. The preparations unmistakably demon- 

 strate the existence of what Browicz has inferred, namely, the existence 

 within the liver-cells of canaliculi communicating directly with the blood- 

 vessels. This is important in regard to the mechanism of nutrition of 

 the liver-cells and in regard to pathological conditions. The specimens 

 date from 1886 (the late Prof. Rutherford's collection), and the canals 

 in question were observed by Prof. Carlier, of Birmingham, who showed 

 them to Rutherford. Unfortunately, the publication of the observation 

 was not then accomplished. 



Nerve-Endings in Human Muscle.1T — Dr. Grabower has been very 

 successful in demonstrating that the nerve-endings in human muscle 

 show essentially the same form and relations as have been described in 

 amphibians and reptiles by Kuhne, Krause, Bremer, and others. The 



* Proc. Eoy. Soc. London, Ixix. (1901) p. 156. 

 t Anat. Anzeig., xxi. (1902) pp. 7-8. 



t SB. Acad. Sci. Wien, 5th Deo. 1901. § Atti Soc. Tosc. Sci. Nat., 1889. 



|| Anat. Anzeig., xxi. (1902) pp. 18-20 (1 fig.). 

 If Arch. Mikr. Anat., lx. (1902) pp. 1-16 (3 pis.). 



