692 



PHYSIOLOGY. 



body. Slight compression of the abdomen will, 

 -without disturbing the arterial supply, drive 

 out a large amount of blood which will be of 

 use for other regions of the body, where it may 

 be applied to the augmentation of their func- 

 tional activity. The front and side abdominal 

 walls are, furthermore, formed of soft, elastic 

 tissues, which, in health, exert an adequate 

 pressure upon the abdominal contents and 

 blood-vessels. If, however, the muscles lose 

 their tone, the walls become flaccid, the veins 

 dilate and become reservoirs for more blood 

 than is needed there, depriving the rest of the 

 body of a part of the fluid requisite for its due 

 nutrition. Here, then, we have an explanation 

 of the office of the waist-belts worn by active 

 peoples and athletics. They help to maintain a 

 due pressure on the abdominal vessels to pre- 

 vent a useless storing of the blood there, and 

 to secure an adequate supply for the parts of 

 the body where it will be demanded. Hence 

 some form of moderate pressure upon the ab- 

 domen may be beneficial to persons leading 

 sedentary Jives and to women. But if the 

 pressure is made extreme, it will prevent in- 

 stead of aiding exercise and activity, will affect 

 the arteries also, and disturb the blood-supply 

 of the abdomen and lower extremities. 



Dr. John A. McWilliam has found that the 

 rule of behavior of the cardiac muscle of cold- 

 blooded animals under the influence of single 

 stimuli that the minimum stimulation is at 

 the same time maximal holds also with the 

 mammalian heart. There occurs a rhythmic 

 rise and fall in the excitability of the organ ; a 

 fall immediately succeeding the occurrence of 

 an effective stimulation, followed by a gradual 

 rise, and this again by subsidence into the 

 phase of quiescence. The facts indicate that 

 all parts of the organ are endowed with inde- 

 pendent rhythmic power, but not in equal de- 

 gree ; and if one portion of the heart possesses 

 a higher power of spontaneons rhythm than 

 the rest of the organ, its rhythm will supersede 

 the inherent rhythm of the other parts, and 

 determine the rate of contraction in the whole 

 organ. The causes determining rhythm are to 

 be sought for at the venous end of the organ, 

 and ultimately in the molecular changes occur- 

 ring deep in the tissue. The propagation of 

 the contraction from auricles to ventricles is 

 mainly effected through the nerves that pass 

 between those parts. 



Dr. E. W. Carlier has explained a method 

 by which human blood may be withdrawn from 

 the body and its fluidity preserved. The finger 

 from which the blood is obtained is greased and 

 plunged into castor-oil before the puncture is 

 made, while every precaution is taken to pre- 

 vent the blood coming in contact with the air 

 or with solid matter. In this way the blood 

 may be preserved in a fluid state for a con- 

 siderable time. As the drops of blood settle 

 slowly in the oil, the corpuscles are seen to fall 

 to the lower part of the drops, while the clear 

 plasma remains above. Prof. Haycraft and Dr. 



Carlier believe that the human blood plasma 

 has never before been demonstrated in an un- 

 altered condition, except microscopically. Co- 

 agulation eventually occurs, because the blood 

 necessarily comes in contact with the sides of 

 the wound made in the finger. 



Continuing his researches on the coagulation 

 of the blood, Dr. Wooldridge endeavors to 

 show that the antecedents of the fibrin are not 

 pure albumens, but fibrinogens consisting of al- 

 bumen and lecithin ; and he attributes great 

 importance to lecithin in the process of coagu- 

 lation. The experiments of Prof. Haycraft 

 and Dr. Carlier in the same line tend to show 

 that the white corpuscles play an important 

 part in the process. 



The distribution of the bloocl-vessels in the 

 valves of the heart has been investigated by M. 

 Darier, who finds that both in the foetus and 

 the adult, in health, there are no vessels in the 

 purely fibre-elastic portion of the auriculo-ven- 

 tricular valves, and that there are none in the 

 chordae tending attached to these valves. 

 The aortic segment of the mitral valve, how- 

 ever, presents at its upper part a vascular area 

 of small extent, not exceeding one sixth of the 

 whole height of the valve; and in the fretus a 

 few muscular fibers accompanied by vessels 

 penetrate the auriculo-ventricular valves, but 

 never extend to the lower fourth of these 

 valves. The semi-lunar valves of the aorta and 

 pulmonary arteries are always destitute of ves- 

 sels ; when vessels are found, therefore, in 

 those non-vascular parts, they may always be 

 regarded as pathological. 



Researches on the blood-vessels of the car- 

 nivora, made by Bellarminoff under the direc- 

 tion of Dr. H. Yirchow, show that the blood- 

 vessels of the eye have a tendency to form 

 rings, from which a large number of fine 

 branches pass posteriorly, and that the ar- 

 rangement is very different in different classes 

 of animals; thus, for instance, the course of 

 the arteries in the eye of a dog, as compared 

 with that of a rabbit, is such that the dog's 

 eye must be turned through an angle of 180 

 in order to make the course of its arteries cor- 

 respond with that of the rabbit's eye. 



Respiration. A simplified method of measur- 

 ing the gaseous interchange during respiration 

 is described by- Prof. Zuntz. In it breathing is 

 carried on, the nose being closed, through a 

 mouth-piece, which is connected by very mo- 

 bile valves with gasometers, which thus meas- 

 ure the volume of the inspired as well as of the 

 expired air. Sample.* of the expired air can be 

 collected at any desired intervals of time, and 

 the amount of oxygen and carbonic acid in them 

 determined. Dr. Loewy has carried out some 

 experiments with this apparatus in order to 

 determine the influence of digestive activity 

 on the process. The respiratory interchange 

 of the patients was determined in the morning, 

 while they were fasting and in a quiescent 

 condition ; they were then given Glaubers'- salt ; 

 as soon as the action of the salt had manifested 



