PHYSIOLOGY. 



cate that the fluid passed through the capsules 

 of the kidney is alkaline, while that secreted 

 by the convoluted portion of the tubules is acid 

 in its reaction. 



The functions of the thyroid gland have been 

 imperfectly understood ; but recent researches 

 have shown that it has an intimate and impor- 

 tant relation with the functions of the brain. 

 Thus, when the gland has been extirpated for 

 g6itre, it has been observed that the subjects 

 steadily lose their mental vigor, the features 

 grow heavy, and the speech slow and dull, the 

 muscular system weakens, the skin turns rough, 

 thick, and hard, and the patient becomes a 

 cretin; but the preservation of the smallest 

 part of the gland prevents these effects. Simi- 

 lar results have been obtained from experi- 

 ments on dogs and cats, which, after the gland 

 has been removed, are attacked with convul- 

 sions, somnolence, and paralysis, and soon die. 

 To account for the relations of this organ to 

 the brain, Liebermeister supposes that the thy- 

 roid gland is the regulatory organ of the en- 

 cephalic circulation, and that its abstraction 

 throws this into chronic disorder. Prof. Bruns, 

 of Tubingen, believes that the gland is either 

 a depuratory which excretes certain substances 

 poisonous to the nervous system, or that it 

 fabricates certain substances indispensable to 

 nervous vigor. 



The Muscular System. Mr. B. Melland has dem- 

 onstrated, by certain methods of gold -stain- 

 ing, that an intra-cellular net-work is present 

 in the muscle-fiber of dytiscus, the bee, frog, 

 lobster, crayfish, and rat. The net- work may 

 also be shown, but not so completely, in the 

 living fiber, and in acetic and osmic acid prepa- 

 rations. Crossing the fiber transversely, united 

 to the sarcolemma, and more or less separating 

 the muscle-fiber into compartments, are net- 

 work partitions the transverse net- works. 

 Running longitudinally down each compart- 

 ment, and joining the dots at the intersections 

 of the fibers of the transverse net-work, is a 

 series of fine rods. This structure serves to 

 explain the transverse striation and other com- 

 plicated appearances presented by the muscle- 

 fiber, and brings into harmony many of the 

 conflicting statements of histologists on the 

 subject. 



The sound heard on auscultating a continu- 

 ously contracting skeletal muscle has generally 

 been ascribed to certain vibrations of the active 

 tissue of such periodicity as to give rise to a 

 tone of from 36 to 40 waves per second. The 

 theory that the normal muscle-sound might be 

 said to have a relationship to a musical tone 

 has been urged as an important link in the 

 evidence tending to prove that normal nerve 

 impulse is intermittent, and that continuous 

 voluntary contraction is composed of snmmated 

 single contractions like the artificial tetanus 

 produced by interrupted stimulations. Fur- 

 ther, the fact that the heart-beat is but a single 

 contraction is urged against the view that the 

 systolic sound is due to muscular tone, because 



it is commonly accepted that the sound pro- 

 duced by contracting skeletal muscles depends 

 upon the regular variations of tension of the 

 tetanic contraction. Believing that this ex- 

 planation of the muscular sound is accredited 

 with a degree of certainty that the facts of the 

 case do not warrant, Drs. E. F. Herroun and 

 G. F. Yeo performed a number of experiments 

 by means of the stethoscope upon certain skele- 

 tal muscles, the conclusions derived from which 

 they thus summarize: 1. That a single con- 

 traction of a skeletal or heart muscle gives rise 

 to motions or vibrations which evoke the res- 

 onant tone of the membrana tympani in the 

 same manner as the tetanic or voluntary con- 

 traction. 2. That the tone heard in voluntary 

 contraction is no evidence of distinct or regu- 

 lar vibrations in the muscle, but merely of 

 motions regular or irregular which produce 

 the vibration of the membrana tympani. 3. 

 That the tone heard in voluntary contraction 

 is therefore no evidence of regular disconti- 

 nuity of natural nerve impulses, but simply 

 depends upon trembling movements due to va- 

 riations either of force or distribution of stim- 

 ulation. 4. That the objection to the first 

 heart-sound being a muscular sound because 

 the systole of the heart is a single contraction, 

 is not valid, since the single contraction of a 

 muscle causes motions or vibrations which call 

 forth the resonant tone of the ear. 



Vegetable Physiology. The fact of a direct con- 

 tinuity between the protoplasmic contents of 

 adjacent cells is an important factor in plant 

 histology, and has only recently been estab- 

 lished. The individuality of the plant-cells, 

 defended by Schleiden, was first criticised by 

 Hofmeister, and more positively and later by 

 Sachs. For Sachs, and also for Strasburger, 

 the plant is only one cohering protoplasmic 

 entity. Nageli also supposes that the proto- 

 plasm of each cell is in direct communication 

 with that of the other cells, by means of deli- 

 cate protoplasmic filaments. These views are 

 supported by the positive observations of nu- 

 merous investigators, beginning with Theodor 

 Hartig, in 1854, whose conclusions are con- 

 firmed in papers by Terletzki, and Dr. Jules 

 Schaarschmidt, of the Royal Hungarian Uni- 

 versity at Kolosvar. The results of the last- 

 named author's investigations, and a general 

 history of the subject, are given in " Nature " 

 for Jan. 29, 1885. 



Prof. W. O. Atwater has made a series of ex- 

 periments to determine whether plants, grown 

 under normal conditions, acquire any consid- 

 erable amount of nitrogen, free or combined, 

 from the ambient atmosphere ; and how the 

 acquisition of nitrogen from the air is affected 

 by abnormal conditions of growth. The ex- 

 periments were made by growing peas in sand 

 which had been purified by washing and ig- 

 niting, and to whtch were applied nutritive 

 solutions containing known quantities of ni- 

 trogen. The amounts of nitrogen supplied in 

 nutritive solutions and seed were compared 



