Apbil 0^ I8S3-X. 



SCIENCE. 



261 



poison, especially on birds. The directions given for 

 preparing the alkaloid, and information as to the 

 quantity of it necessary to produce lethal results, have, 

 however, been very deficient. Budwin, desiring to 

 obtain further information on the latter point, arrives 

 at results which throw doubt on the whole matter. 

 He finds that fresh extract of lOU cub. cm. of human 

 saliva subcutaneously injected does no harm to frogs, 

 moles, or pigeons. — (Arch. path. anat. phys., xci., 

 1883, 190. ) H. N. M. [569 



The influence of heat and cold upon muscles 

 poisoned by veratria. — It has for some time been 

 known, chiedy from the work of V. Bezold, that ve- 

 ratria exercises a remarkable influence upon muscular 

 contractions. A rapid and powerful contraction is 

 followed by an extraordinarily slow relaxation. In 

 the hope that closer study of the veratria muscle- 

 curve might throw some light upon the nature of a 

 muscular contraction, Lauder Brunton and Cash 

 have made a fresh study of it, especially investigating 

 it under different temperatures. Their work, while 

 not giving much information in regard to this pri- 

 mary point, has led to some interesting results. They 

 find that the influence of veratria varies much with 

 the temperature of the muscle experimented upon. 

 Up to a certain limit, heat increases the effect of the 

 drug; cold diminishes it. Exposure to extremes of 

 heat or cold not suflicient to kill the muscle pre- 

 vents entirely the manifestation of the usual veratria 

 symptoms. The authors point out, that the modifi- 

 cations which temperature-changes bring about in 

 the action of veratria on muscle suggest that temper- 

 ature may modify the influence of other drugs, not 

 only on muscles, but on nerves and nerve-centres. 

 Accordingly the diff^-ent action of drugs on differ- 

 ent animals, or on the -same animal in various physio- 

 logical and pathological conditions, may be due in part 

 to temperature differences, physiological or pathologi- 

 cal, of the organisms to which they are administered. 

 — (Journ. of physiol., iv. 1.) h. n. m. [570 



Conditions influencing the amylolytic action 

 of saliva. — Working with saliva previously carefully 

 neutralized, — -a precaution which has not been always 

 taken by previous observers, but which is clearly ne- 

 cessary on account of the variable acidity or alkalin- 

 ity of different specimens of saliva, — Langley and 

 Eves arrive at the following conclusions: 1°. Neu- 

 tralized saliva converts starch into sugar much more 

 actively than unneutralized. 2°. .0015 per cent H CI 

 distinctly diminishes the amylolytic action of ptyalin. 

 3°. Sodium carbonate also diminishes the activity of 

 previously neutralized saliva, and more the more of 

 the alkaline salt is present. 4°. .005 per cent HCl 

 has a very obvious destructive influence on ptyalin. 

 5°. Sodium carbonate has a very slight destructive 

 power, but greatly retards the action of the salivary 

 ferment. 6°. Neutralized saliva converts starch into 

 sugar more quickly in the presence of neutral peptone 

 than in the presence of peptone plus dilute HCl. 

 7°. The larger the percentage of acid in proportion 

 to the peptone, — that is to say, the more acid unem- 

 ployed in combining with the peptone, — the more 

 marked the injurious influence of the acid. Even 

 before the peptone is completely saturated with acid, 

 the injurious effect, due apparently to the presence 

 of acid-peptone, becomes obvious. 8°. Ptyalin is de- 

 stroyed by acid combined with peptone much more 

 slowly than by the same amount of acid without the 

 peptone. 9°. When peptone is present, the deleterious 

 influence of sodium carbonate is greatly diminished. 

 Not merely peptone, however, but myosin, alkali albu- 

 men, and acid albumen act in the same protective 

 manner. The authors conclude that all ptyalin is 



destroyed in the stomach very soon after that first brief 

 stage of gastric digestion in which no free acid is 

 present. — {Juurn. of physiol., iv. 18.) h. n. m. [571 



Mammals, 

 Caudal end of vertebrate embryos. — In his 



studies on the development of Melopsittacus, Braun 

 observed that a constriction is formed around the end 

 of the tail, which leads to the construction of a termi- 

 nal knob, connected by a thin stalk with the base of 

 the tail. Into this nodulus caudalis the chorda and 

 medullary tube originally extend; but they afterward 

 withdraw from it, leaving the nodulus, a ball of meso- 

 derm covered by ephithelium, to be finally resorbed. 

 This discovery led Braun to search for similar struc- 

 tures in mammals, and he now publishes his results. 

 His investigations were made principally on sheep em- 

 bryos, and observations were also made on those of 

 other species. He finds an homologous structure, 

 having, however, more usually a thread-like form. In 

 sheep it may be readily seen in most cases when the 

 tail is from 1. 5 to 3 mm. long. His general results 

 are: 1°. The tail of mammalian embryos consists 

 of two parts, — an anterior or basal vertebrate ; and 

 a posterior invertebrate and smaller portion, which, 

 from its usual form, may be called the caudal thread. 

 2°. The vertebrate portion may be partly or wholly 

 embedded in the body (internal tail), and terminates 

 at the sacral vertebrae in front; the division of the 

 tail which protrudes is the external tail. 3°. The 

 caudal thread contains originally the terminal por- 

 tions of the chorda dorsalis, tire medullary tube, and 

 the caudal gut (schwanzdarm). These are the first 

 parts of the thread to be resorbed ; the rest disappears 

 later, the epidermal covering lasting longest. 4°. The 

 caudal gut is a rectal coecum ; before it is resorbed, it 

 breaks up into single parts, of which those in the tip 

 of the tail endure the longest. 5°. The chorda dor- 

 salis projects beyond the lastvertebra, its ending being 

 often forked or contorted. 6°. The medullary tube 

 reaches to the tip of the tail or the base of the caudal 

 thread, and its posterior end is probably resorbed. 

 Braun further believes that he has found traces of a 

 neurenteric canal in sheep embryos. He adds a dis- 

 cussion of the tail in human embryos. Finally he 

 homologizes with the embryonic caudal thread, the 

 soft coccygeal appendix of Innus pithecus, and simi- 

 lar structures found abnormally in the chimpanzee, 

 orang-outang, and man, and gives citations to prove 

 that the caudal thread exists in human embryos. — 

 {Arch, anal.rjhysiol., anat. abth., 1882, 207.) c. s. m. 



[572 

 Mucous layer of the skin. — Ranvier has made 

 sections of the human skin, hardened in" bichromate 

 of ammonia (2%) for two or three months, and then 

 with gum and alcohol. In these the intracellular 

 network is well shown by haematoxylin. The fibres 

 of the network project beyond the cell, and establish 

 the union between the cells. In the intercellular 

 spaces these fibres are thicker than within the cells: 

 they have therefore acquired an additional envelope. 

 Eanvier further argues against considering the threads 

 as protoplasm, but maintains that the clear substance 

 in which they are embedded is the true protoplasm 

 in all cells derived from the ectoderm. This is espe- 

 cially maintained for the central nervous system. 

 (His arguments do not appear convincing). — [Comp- 

 tes. rend., xcv. 1374.) c. s. m. [573 



ANTHROPOLOGY. 



The archeology of Russia. — Count Ouwarof 

 of Moscow published, in 1881, a work on the prehis- 

 toric archeology of Russia. As to paleolithic. man. 



