366 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Growth of Parts of Rats and of the Whole. — Shinkishi Hatai 

 {Amer. Jourii. A/iat., 11)18, 24, 71-89,4 figs.)- The increase of weight 

 in epididymis, pancreas, stomach, and submaxillary glands is compared 

 with that of the body as a whole for each millimetre of length from 

 •47 mm. (weighing 4* i) grm.) to 250 mm. (weighing 448" 5 grm.). Some 

 results may be noted. Before puberty the weight of the epididymis is 

 approximately one-sixth that of the testes, after puberty about a third. 

 The weight of the stomach is about one-ninth of the alimentary tract, 

 except in the newborn rat, where it is relatively heavier. The females 

 have a heavier pancreas than males of the same weight. J. A. T. 



Proportion of Sexes in Whitefish. — Eaymond Pearl (Report 

 Michigan Acad. Sci., 1916, 17, 76). There is great dearth of definite 

 statistics regarding the normal sex-ratios of even the commonest animals. 

 In unselected catches (five days) of Goregonus albus taken in deep water 

 gill-nets in Lake Erie, there were 386 males to 455 female, a ratio of 

 848 males to 1000 females. J. A. T. 



b. Histology. 



Lining of Perivascular Spaces. — Kaethe W. Dewey {Anat. 

 Record, 1918, 15, 1-26, 9 figs.). An apparently exceptional behaviour 

 towards vital stains is exhibited by the endothelial cells lining the 

 perivascular spaces, or, if the existence of such cells be denied, by the 

 perivascular connective-tissue within the brain and spinal cord. 



Unlike such cells in the perivascular connective-tissue in other 

 organs and tissues, they do not habitually take up the vital stain, but do 

 so only under the influence of stimuli from pathological conditions. 



Affinity for the vital stain is absent, in general, in the endothelial 

 cells of the inner lining of arteries, veins, and capillaries, but present in 

 the capillaries and venules of the spleen, the capillaries of bone-marrow, 

 the blood sinuses of hseraal glands, and the Kupffer cells of the liver, 

 ft is absent, in general, in the endothelial cells lining the inner wall of 

 the lymph-vessels outside the organs ; present in the lymph-channels 

 within organs except the brain and spinal cord. " With reference to 

 the central nervous system, affinity for the vital stain is absent, in 

 general, in the perivascular spaces within the brain and spinal cord ; 

 present in these conditionally and in focahzed distribution in the 

 presence of pathological stimuli, in general, within the membranes along 

 channels conveying lymph or cerebrospinal fluid." J. A. T. 



Heart-muscle of Embryo Chick.^ — E. D. Congdon {Anat. Record, 

 1918, 15, 135-50, 10 figs.). The heart of chicks younger than the 

 sixteen- or seventeen-somite stages, when rhythmical contraction begins, 

 has a sarcoplasmic structure whose optical section is a net consisting of 

 two systems of parallel lines intersecting to cut off spaces approaching a 

 square form. They measure in the fixed material abott 0*8 micron on 

 a side. The apparent net is probably produced by three systems of 

 intersecting membranes which form hexahedral compartments. At all 

 the intersections of three planes there are small uniform mitochondrial 



