March io, 1892] 



NATURE 



451 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, February ii. — "Contributions to the 

 Physiology and Pathology of the Mammalian Heart." By 

 Prof. Roy, M.D., F.R.S., and J. G. Adami, M.A., M.B. 



The authors have spent several years in attempting to give 

 to the study of the intact mammalian heart the accuracy which 

 has been attained in the study of the heart of cold-blooded 

 animals. They described two instruments which had been 

 found by them to be of especial value : one which they term the 

 cardiometer (a form of cardiac plethysmograph or oncograph) ; 

 the other, the myocardiograph, by means of which records were 

 obtained of the contraction and expansion of the muscle 

 between two points upon the surface of either ventricle, or of 

 ventricle and auricle simultaneously. They pointed out the 

 ease wherewith cardiac tracings may be misinterpreted if certain 

 elements of the mechanics of the heart be not constantly kept in 

 mind. Thus, if, when the chambers of the heart become ex- 

 panded, there is a lessening of the extent to which at each 

 systole the muscle fibres contract, this does not mean that the 

 contractile force is weakened : for with increase in the contents 

 of the cavities of the heart there is increased strain (or weight) 

 thrown upon the walls, and a comparatively slight diminution in 

 the circumierence of the expanded ventricle suffices to expel the 

 same amount of blood, whose expulsion, when the ventricle is 

 but little expanded, is accompanied by great diminution in cir- 

 cumference. Thus, in considering the action of the vagus upon 

 the heart, it was shown that stimulation of this nerve does not 

 cause loss of ventricular force of contraction. Moderate stimu- 

 lation induces weakening or paralysis of the auricles, accompanied 

 by ventricular dilatation. This dilatation is due to the increased 

 venous and intraventricular pressure accompanying the slowed 

 rate of beat. And though, as shown by the myocardiograph, 

 there is now lessened systolic contraction of the ventricular wall, 

 and also lessened output in a givt-n time, each individual con- 

 traction leads to the expulsion of an increased quantity of blood. 

 The only direct action of the vagus upon the ventricles, accord- 

 ing to the authors, is a diminution of the excitability of the 

 ventricular muscle. Upon continued fairly strong vagus excita- 

 tion the auricular rhythm is weakened or inhibited, and does not 

 suffice to set up the normal "sinus," or post-auricular rhythm 

 of the ventricles ; so for a time the ventricles usually cease to 

 beat ; but soon the independent idio-ventricular rhythm mani- 

 fests itself, the same that is to be seen when, after ihe methods 

 of Wooldridge or Tigerstedt, the mammalian auricles and 

 ventricles are cut off from one another ; or, again, shows itself 

 after muscarin poisoning. Experiments of the authors and 

 early observations of Einbrodt were mentioned proving this con- 

 tention. With a certain degree of vagus excitation, irregularity 

 of the ventricles results in consequence of the sinus and idio- 

 ventricular rhythms interfering with one another. In the dog 

 this is the common form of irregularity ; probably this is also 

 true for man. 



The authors conclude that the term nervi augmeniores is 

 better and more comprehensive than that of nervi accelerantes 

 cordis. Excitation of these nerves in the dog leads more often to 

 augmentation in the force than in the frequence of contraction : 

 the two effects do not by any means go hand -in-hand. 



Vagus excitation relieves the heart of work, and therefore of 

 waste, to as great an extent as is compatible with a continuance 

 of the circulation ; the vagus may therefore be looked upon as 

 primarily the protective nerve of the heart, and secondarily it 

 was shown to act in the interests of the central nervous system ; 

 while the presence in the sciatic and other mixed nerves of 

 fibres which cause reflex vagus excitation would seem to indicate 

 that the nerve may be used by other parts of the body to 

 diminish the output of the heart, and so to reduce the activity of 

 the circulation as a whole. The idio-ventricular mechanism 

 must be locked upon as a means whereby arrest of the circula- 

 tion — and death — is prevented when the vagus action exceeds a 

 certain limit. 



The augmentor nerves, on the other hand, increase the work 

 and tissue waste of the heart, this organ being sacrificed for the 

 needs of the economy until the vagus is called into play by 

 cardiac reflex. The output is increased, and the ventricles 

 are enabled to pump out their contents against heightened 

 arterial blood pressure. 



Other considerations dealt with by the authors were : the 

 mode of interaction of the vagi and augmentores, and factors 



NO. TI67, VOL. 45] 



other than nervous affecting the force of the heart's contractions ; 

 for example, the blood pressure in the coronary arleries ; 

 changes in the volume and in the constitution of the blood, 

 asphyxia, fatigue, and organic disease ; the part played by the 

 nerves in all these cases being especially taken into considera- 

 tion. 



February 25. — " The Electric Organ of the Skate : Observa- 

 tions on the Structure, Relations, Progressive Development, and 

 Growth of the Electric Organ of the Skate " By J. C. Ewart, 

 M.D., Regius Professor of Natural History, University of Edin- 

 burgh. Communicated by Prof. J. Burdon Sanderson, F. R.S. 



After referring to the observations of Stark, the discoverer of 

 the skate's electric organ, and to the work of Robin, Leydig, 

 Babuchin, and others, the author describes the arrangement of 

 the muscles in the tail of Selachians with a view to determining 

 which muscles in the skate are transformed into the electric 

 origans. 



By comparing the caudal muscles of Scy Ilium, Lamna, 

 Myhobatis, and Raia, it is made out that, while the middle row 

 of mu^-cular cones remains unaltered in the sharks and rays, it is 

 transformed into a more or less perfect electric organ in the 

 skates the various members of the genus Raia. It is pointed 

 out that, while the middle row of muscular cones is transformed 

 in Raia into electric cones, the two adjacent rows of cones, as in 

 the rays and certain sharks, diminish in size, and in some cases 

 disappear about the middle of the tail. 



In considering the structure of the organ, it is stated that, 

 when the various modifications are taken into consider ition, it 

 may be described as consisting of a series of electric cones made 

 up of more or less completely metamorphosed muscular fibres. 

 Twenty-eight distinct cones were counted in the organ oiR. baits. 

 The first, which in a half-grown fish measured 5 cm. in length, 

 was all but completely invested by the last unaltered muscular 

 cone. From the first to the tenth the cones slightly increased in 

 length ; but from the eleventh they diminished in length, the 

 twenty-sixth measuring only 075 cm. Beyond the twenty-eighth 

 there were from six to eight incomplete cones. 



In transverse sections the anterior third of the organ was seen 

 to present an oval or rounded form, while the middle and 

 posterior thirds were less regular, owing to the organ coming 

 into contact with the vertebral column, and being grooved by 

 the dorsil and ventral muscles. 



The cones are described as consisting of numerous loculi or 

 chambers, each having an electrical k suspended by nerve fibres 

 from its anterior wall, and occupied in front and behind the disk 

 with gelatinous tissue. 



It is estimated that each organ in R. batis is made up of about 

 10,000 electric elements, i.e. about 20,000 in the two organs. 

 Torpedo marmorata has about 500,000, and T. giganlea about 

 1,000,000, elements in the two batteries, all consideraL)ly larger 

 than those of the skate. 



I he layers of the electric disks, the electric, striated, and 

 alveolar, are described in detail ; and the vari us views as to the 

 termination of the nerve fibrils in the disk are referred to. 



In the chapter on the progressive growth of the organ a table 

 is given to show that in R. batis the organ, after a time, grows 

 at a greater rate than the tail in which it is lodged : eg. in fish 

 60 cm. in length the tail measures about 28 cm., and the electric 

 organ 22*5 cm, ; well-formed disks having an area of 0"8 to 

 I sq mm. In fish 225 cm. in length the tail measures 85 cm., 

 the organ 70 cm., and the disks have an area of about 2-08 sq, 

 mm. In fish from 25 5 to 30-5 cm. in length the organ is from 

 1278 to i4'o cm., and weighs 0"5 to 0'6 gram ; in fish from 

 83-5 to 91 25 cm. the organ is from 30*50 to 34*25 cm., and 

 weighs from 60 to 80 grams ; in fish 157 cm., the organ 

 measures 48*25 cm., and weighs 25*00 grams ; while in 225 cm. 

 fish the organ, which measured 70*00 cm., weighed 15600 

 grams. These facts, especially the great size and weight of the 

 organ in large skate (about 7 feet in length), do not seem to 

 point to the skate's organ being in process of degeneration ; 

 more especially as the increase in size is not accompanied by 

 any histological changes of a retrogressive nature, the largest 

 organ examined being apparently as perfect as that of Torpedo 

 and Gymtiotus. 



In discussing the organ from a physiological point of view, 

 reference is made to the investigations of Sanderson and Gotch, 

 and it is pointed out that, when the electric plate is taken as the 

 unit, the value per square millimetre of the single plate of the 

 skate is in all probability equal to, if not greater than, that of 

 the torpedo. 



