140 SUMMARY OF CURRENT RESEARCHES RELATING TO 



tion of the musculature and connective-tissues of the gut in the families 

 of birds studied. 



Micro-Chemistry of Nerve-cells.* — Mr. F. H. Scott supports the 

 view that all iron-holding nuclein compounds are derived from pre- 

 existing ones, and that in mitosis all the iron-holding substance of the 

 cell is in the nuclear chromatin. The Nissl granules are morpho- 

 logical elements of the nerve-cell, of a nucleo-proteid nature, containing 

 " masked " iron and organic phosphorus, and are derived from the 

 nuclear chromatin of the germinating cells. The nucleolus of the nerve- 

 cell has an oxyphile centre with a basophile covering. The latter seems 

 to correspond to the original kinetic chromatin of the germinal cells, 

 and, like the oxyphile nuclear substance, contains iron and phosphorus. 

 All the three nuclein compounds of the adult nerve-cell are derived 

 from the mitotic chromatin of the primitive nerve-cell. It follows that 

 the Nissl granules are constituted of chromatin that has diffused from 

 the nucleus into the cytoplasm. 



Relation of Nerves to Muscle.f — Dr. Chr. Sihler has studied this 

 question in the frog, and finds that the terminal fibrils of the motor 

 nerves lie upon the sarcolemma, and are invested by Schwann's sheath 

 and by nuclei up to their ends. Whether or not these membranes 

 actually separate the nerve and muscle substance at the points of contact, 

 is still undetermined, but the author considers that more stress should 

 be laid on these points of contact than on the nerve-endings. In the 

 frog, and in certain muscle-fibrils in the snake, Henle's sheath is open 

 and fuses with nothing, whereas in the typical end-plate it covers the 

 terminal fibrils like a cap. In the frog there is no " sole," so that this 

 structure can form no necessary part of the stimulating apparatus of the 

 muscle. The " sole " substance when present must be regarded as the 

 protoplasm of the endothelial cells forming the terminal swelling of 

 Henle's sheath ; the nuclei of the end-plate belong partly to these cells, 

 partly to the terminal part of Schwann's sheath. In unstriped muscles 

 there are no end-plates, but merely a terminal network of nerve-fibrils. 

 In connection with the capillaries in the frog there is an even richer 

 supply of nerve-fibrils than in the muscular tissue, the fibrils ending as 

 in unstriped muscle. Their function is complex, for they are connected 

 both with the sensory nerves and with the nerves which surround the 

 arteries and veins, and so influence the capillaries as to produce an in- 

 creased transudation of lymph, and not a mere widening of the lumen. 

 This active change in the walls of the capillaries the author compares 

 to the contraction of muscle. 



Histology of the Blood, f — Profs. P. Ehrlich and A. Lazarus have 

 made a very important contribution to hseinatology in this treatise on 

 the cellular elements of the blood in health and disease. That lympho- 

 cytes and leucocytes are quite distinct types of white blood-corpuscles ; 

 that the cell-granules are of great importance ; that chemiotaxis plays 

 an important part in the emigration of cellular elements from marrow to 



* Trans. Canadian Inst., vi. (1890) pp. 405-88 (1 pi.). 

 t Zcitschr. wiss. Zool., lxviii. (1900) pp. 323-78 (2 pis.). 



t ' Histology of the Blood: Normal and Pathological.' Edited and translated 

 by W. Myers. Cambridge, 1900, 8vt>, xii. and 216 pp. 



