540 



PHYSIOLOGY. 



called a bioplasma, which performs all the func- 

 tions of life, and is, substantially, a cell. Repro- 

 duction is under this view discontinuous growth 

 due to chemical assimilation as described, while 

 the figures accompanying cell division are the 

 morphological consequences of the chemical as- 

 similative powers of the bimolecules constituting 

 the cell. 



Respiration. A special interest is attached to 

 hibernating mammals, because the rise which oc- 

 curs in the temperature of their bodies during the 

 awakening from torpidity is greater and more 

 rapid than any other elevation of temperature 

 that can be observed in animals. Hibernation is, 

 moreover, a physiological condition in which the 

 processes of combustion are reduced to the lowest 

 ebb compatible with the life of mammals. During 

 this winter sleep the animal responds to changes 

 in the external temperature in a similar way to 

 that shown by a cold-blooded animal. In sum- 

 mer, when it is awake and active, it has the 

 characteristics of a w 7 arm-blooded animal. From 

 his studies of the phenomena in the marmot, 

 M. S. Pembrey has found that in the active 

 animal 'the respiratory change differs somewhat 

 from that of the rabbit. The discharge of water 

 from the lungs is much smaller, and greater varia- 

 tions are seen in the respiratory quotient. During 

 torpidity the respiratory change is small and char- 

 acterized by the small respiratory quotient, 0.53. 

 The sleeping animal gains in weight, for although 

 it loses water and carbonic dioxid, it absorbs a 

 greater weight of oxygen. The amount of mois- 

 ture given off' is small, and relatively to the car- 

 bon dioxid dissolved is much smaller than in the 

 active animal. The respiratory quotient 0.53 ob- 

 served in the hibernating mammal is probably to 

 be explained by the combustion of fat and the 

 formation of sugar, which is stored up as glycogen 

 in the liver and muscles. During the awakening 

 or passage from torpidity to activity, a great in- 

 crease takes place in the respiratory exchange, 

 and the respiratory quotient rises. The discharge 

 of moisture is only slightly augmented, and thus 



the ratio 



CO; 



H 2 



is even as high as 16, whereas the 



corresponding figure for the active animal is 

 about 3. During the awakening, increased mus- 

 cular action is observed, even violent shivering. 

 The metabolism at this stage is probably the con- 

 version of glycogen into sugar and the combus- 

 tion of the latter during muscular contraction; 

 at the same time there appears to be a combus- 

 tion of fat and the formation of more glycogen 

 and sugar. The respiratory movements show in 

 frequency and type a relation to the animal's in- 

 ternal temperature and activity. Periodic breath- 

 ing, Cheyne-Stokes respiration, is frequently 

 seen when torpidity is not profound. During the 

 stage of most rapid rise in the temperature of the 

 awakening marmot shivering is observed, espe- 

 cially in the anterior half of the body, and the 

 temperature of the mouth is several degrees above 

 that of the rectum. 



In experiments on the cat, T. G. Brodie found 

 that the immediate action of intravenous injec- 

 tion of blood-serum is to cause arrest of inspira- 

 tion, inhibition of the heart, and vascular dilata- 

 tion, and that the effect persists for some time. 

 The symptoms are reflex and are almost entirely 

 absent if the vagi be previously divided in the 

 neck. The effect is due to excitation of the pul- 

 monary nerves, and is cut out by division of the 

 pulmonary branches of the vagus, but not by divi- 

 sion of the cardiac or lower branches. Repetition 

 of the injection leads to the production of an im- 

 mune state. The active substance in the serum is 



a proteid of the albumin class, and is coagulated 

 on being heated to 86 C. It is produced only 

 when the blood clots. Serum obtained from 

 plasma is inactive. 



Of the branches of the vagus, excitation of the 

 central end of which causes reliex inhibition of 

 the heart, the pulmonary libers were found by 

 T. G. Brodie and A. F. Russell to be in dogs 

 the ones that produce the most marked reaction. 

 The cardiac fibers were much less effective, and 

 the branches below the pulmonary were still less 

 so. The connection of the respiratory tract with 

 the cardio-inhibitory center is very close. Thus 

 stimulation of the nasal mucous membrane at 

 once arrests the heart. Stimulation of the laryn- 

 geal mucous membrane is only a little less effec- 

 tive. Stimulation of the trachea and large 

 bronchi is apparently without effect, but stimu- 

 lation of the alveolar nerves is about as effective 

 as of the laryngeal. These nerves produce a 

 result when excited electrically in their course 

 from the mucous membrane or when stimulated 

 mechanically or chemically in the mucous mem- 

 brane itself. Excitation of the pulmonary nerves 

 also acts upon the respiratory and vasomotor 

 centers, producing arrest of respiration and fall 

 of blood-pressure. Alveolar nerves can be excited 

 chemically by inhalation through a tracheal tube 

 of irritant vapors or by injection of such sub- 

 stances as serum or egg white. Division of the 

 pulmonary nerves on both sides abolishes the 

 effect on the cardiac, respiratory, and vasomotor 

 centers. 



Circulation. By means of a new method for 

 investigation of the action of drugs on the mam- 

 malian heart, Dr. T. G. Brodie, of London, found 

 that chloroform depressed the working capacity 

 vastly more than ether in ethylene chlorid. Supra- 

 renal extract much increased the amount of work 

 performed by the heart, and also its rate of beat. 

 It acted as an antidote to chloroform. If it was 

 administered before chloroform it was found that 

 the heart could withstand much larger doses of 

 that dr,ug. Moreover, a heart deeply injured by 

 chloroform would rapidly and completely recover 

 if suprarenal extract was administered. It had 

 been constantly found in the course of the re- 

 search that the heart was very sensitive to the 

 blood of different mammalian species. Thus the 

 heart of the dog went quickly into fibrillar inco- 

 ordination unless fed with dog's blood; ox blood 

 and other kinds of blood acting deleteriously at 

 once. 



In experiments of Dr. F. S. Locke, of London, 

 on the action of dextrose on the mammalian heart, 

 the heart, removed from a freshly killed rabbit, 

 was washed clear from blood and suspended freely, 

 and an arrangement was made for recording the 

 contractions by means of a lever attached to the 

 apex. Kept at a temperature of 35 C., and fed 

 with a moderate Ringler's fluid, the contractions 

 gradually grew feeble and ultimately very weak. 

 If, then, oxygen under pressure was introduced 

 into the fluid feeding the coronary arteries, the ' 

 beats rapidly increased and remained good for 

 about an hour; then they once more diminished 

 and failed. Dextrose then added to the feeding 

 fluid to the extent of 1 per cent, restored the beat, 

 and it continued with hardly noticeable failure 

 for about ten hours. The beating fell at once if 

 for the dextrose in the feeding fluid the oxygenated 

 Ringler solution without any dextrose was sub- 

 stituted, but the beat was restored on returning 

 again to the sugared fluid. Sucrose, levulose, and 

 other sugars as yet tried failed to give evidence 

 of this restorative power. 



It is shown by Prof. Hedon, of Montpellieiv 



