March 3. 1898 J 



NATURE 



429 



The general conditions for the existence of such systems are 

 determined, and are worked out in more detail for a particular 

 case of spherical aggregate. It is found that the motion in 

 meridian planes is determined from a certain function ;^ in the 

 usual manner. The velocity along a parallel of latitude is 

 given by v =J{y^)jp where p is the distance of the point from the 

 straight or polar axis. The function ij* satisfies an equation of 

 the form (when expressed in polar coordinates) 



dt^ r* dfF 



r" de 



where F and / are both functions of ^. The case F uniform* 

 and/oc(f( is treated more fully. \i f = K^ja where a is the 

 radius of the aggregate, 



* = A{L(*f) 



5jw} 



sin-fl. 



The most striking and remarkable fact brought out is that as 

 A increases we get a periodic system of families of aggregates. 

 The members of each family differ from one another in the 

 number of layers and equatorial axes they possess. According 

 to the number of independent axes they are called singlets, 

 doublets, triplets, .Jcc, in contradistinction to more or less 

 fortuitous or arbitrary compounds of the former which are con- 

 sidered later and called monads, dyads, triads, &c. Of these 

 families two are investigated more in detail than the others, 

 both because they are specially interesting in their properties 

 and because they serve as limiting cases between the different 

 series. In one family (the X.^ family) all the members remain at 

 rest in the surrounding fluid. In the other (the A.j family) a 

 distinguishing feature, common to all the members, is that the 

 stream lines and the vortex lines are coincident. 



The parameter A gives the total angular pitch of the stream 

 lines on the outer current sheet. The first aggregates— with 

 ^< 57637 (the first A,.^ value)— behave abnormally. Beyond 

 these we get successive series, in one set of which the velocity 

 of translation is in the same direction as the polar motion of the 

 central nucleus, in the alternate set the velocity is opposite, and 

 the aggregate regredes in the fluid as compared with its central 

 'Aggregate. 



At the end of the paper a theory of compound aggregates is 

 developed. It is not worked out in detail in the present com- 

 munication, but the conditions are determined for dyad com- 

 pounds, whilst a similar theory holds for triad and higher ones. 

 Each element of a poly-ad may consist of singlets, doublets, 

 &c. The equations of condition allow three quantities arbitrary 

 — as for instance ratio of volumes, ratio of primary cyclic con- 

 stants, and ratio of secondary cyclic constants. 



At the end of the abstract, illustrations of the relations of the 

 theory to the vortex cell theory of the ether, and to the periodic 

 law of the chemical elements are touched upon. 



February lo. — "The Development and Morphology of the 

 Vascular Sy.stem in Mammals. The Posterior End of the 

 Aorta and the Iliac Arteries." By Alfred H. Young, M.B., 

 F.R.C.S., and Arthur Robinson, M.D. 



Though numerous observations have been made on the 

 development of the systemic aorta and on the aortic arches, 

 including their modifications and transformations at the head end 

 of the embryo, but little attention has hitherto been given to 

 the development and modifications of the primitive vessels and 

 the aortic arches at the caudal end. 



The view that the primitive aortae are prolonged backwards 

 from the dorsal region into the tail, and that, fusing there, they 

 form a caudal aorta — the middle sacral artery— seems to be 

 generally accepted by embryologists. The iliac arteries are 

 accordingly regarded as segmental vessels. 



Observations on the development of the posterior end of the 

 aorta and its terminal branches in mammals point, however, to 

 very different conclusions. 



The primitive aortse are not directly continued into the 

 middle sacral artery, but into primary caudal arches, one on 

 each side, the ventral continuations of which either fuse together 

 to form a common vitello-allantoic stem, as in rodents, or they 

 remain separate and form the ventral parts of the allantoic 

 arteries, as in carnivores, ruminants and man. 



The middle parts of the primary caudal arches disappear and 

 are replaced by "secondary" caudal arches which lie to the 

 outer sides of the Wolffian ducts. In rodents and man the 

 secondary arches are transformed into the common and internal 



NO. 1479. VOL. 57] 



iliac arteries and the dorsal parts of the hypogastric arteries, 

 whilst in carnivores they are probably transformed into the pos- 

 terior part of the adult aorta and into the internal iliacs and 

 dorsal parts of the hypogastric arteries. 



The vessels, which are to be looked upon as the ix)sterior 

 continuations of the primitive aorta in the adult in man, rodents, 

 &c.. are the common iliac, internal iliac, and hypogastric 

 arteries, and in carnivores, &c., the internal iliac and hyix>gastric 

 arteries. 



The common and internal iliac arteries are not segmental 

 vessels, their branches may be. 



The middle sacral artery is a secondary branch, probably 

 representing fused segmental vessels. 



The permanent adult aorta, in so far as it is formed by the 

 primitive dorsal aortse, ends posteriorly either at the bifurcation 

 into the two common iliac arteries or at a point corresponding to 

 this bifurcation, when by more extensive fusion involving the 

 dorsal parts of the secondary arches there are no common iliacs, 

 and the external and internal iliac arteries appear to arise 

 directly and separately from the aortre. In each case the con- 

 tinuity of the primitive aorta is interrupted ; the primary caudal 

 arches are replaced by secondary caudal arches, after which the 

 continuations of the aorta are represented by the vessels into 

 which the secondary caudal arches are ultimately transformed. 



These conclusions are further supported by more extended 

 observations on the anatomy of the posterior end of the aorta, 

 and its terminal branches in mammals, and on the abnormalities 

 they present in man. 



"Further Observations upon the Comparative Chemistry of 

 the Suprarenal Capsules, with Remarks upon the Xon-existtnce 

 of Suprarenal Medulla in Teleostean P^ishes." By B. Moore, 

 M.A., and Swale Vincent, M.B. 



In a previous communication these authors have shown that 

 the paired segmental suprarenals of Elasmobranchs contain a 

 chromogen giving the same reactions as that of the medullary 

 portion of the suprarenal capsule of higher vertebrates, while 

 the inter-renal body in the same order of fishes contains no such 

 chromogen. 



Now the suprarenal bodies of Teleosts do not contain the 

 physiologically active principle which is characteristic of supra- 

 renal medulla, and the natural conclusion would seem to be that 

 the representative of the medulla is absent. But further evidence 

 is desirable. 



A decoction from the suprarenal bodies of Gadtis /norrhua 

 and Angnilla angtiilla was carefully tested for the chromc^en, 

 with entirely negative results. The lymphoid "head-kidney" 

 was also tested, as well as other portions of the kidney, but no 

 trace of the chromogen was found. 



From these observations, combined with those previously 

 made, the authors are forced to the conclusion that the medul- 

 lary portion of the suprarenal capsules is nonexistent in 

 Teleostean fishes. 



" The Effects of Extirpation of the Suprarenal Bodies of the 

 Eel (Angnilla angnilla)." By Swale Vincent, M B. 



Teleostean fishes, having only suprarenal cortex, seemed to- 

 offer an admirable opportunity of testing how far these " cortical 

 glands " were essential to the life of the animal. Accordingly,^ 

 a series of extirpation experiments were performed upon the 

 eel. 



In three cases in which the animals survived the operation^ 

 they appeared quite lively soon after being put back in the 

 tank. One survived twenty-eight days, another sixty- four days, 

 and a third was killed on the 119th day. These experiments 

 show that an eel will survive the operation of extirpation for a 

 very much longer time than mammals or frogs ; and the difference 

 is so striking that one must attribute it to the absence of 

 medulla in Teleosts, and must assume that the cortical gland is 

 not absolutely essential to the life of the animal. The longest 

 time that a frog will survive removal of its capsules is twelve or 

 thirteen days. Mammals usually die in a day or two. 



The validity of these experiments depends uf)on the actual 

 removal of all suprarenal. This was verified in two ways, (i) 

 Previous study showed that the bodies in the eel are never more 

 than two. (2) All three eels were dissected post-mortem, and 

 no trace of suprarenal was found left behind. 



Chemical Society, February 17.— Prof. Dewar, President, 

 in the chair. — It was announced that the following changes in 

 the Officers and Council were proposed by the Council. As 



■•ties. 



