Jan. 



1SS9] 



2\A TURE 



335 



man followed injection of the comma bacillus into the stomach 

 of the guinea-pig, care being taken lo neutralize the acid pro- 

 ducts which are fatal to the organism. —Prof. Tait de-;cribed some 

 preliminary observations with a large rotatory-polarization 

 spectroscope. In this apparatus the light passes through a slit 

 and collimator, a Nicol's prism, a train of cylinders of quartz, a 

 double image prism, and an ordinary direct-vi-iion spectroscope. 

 The instrument is so arranged that the two spectra produced are 

 in exact juxtaposition side by side, eacli spectrum being alter- 

 nately crossed by dark interference bands correspon ling to 

 successive rotations of the plane of polarization through 180°. 

 A scale is thus applied to thespec'rum, and the interval between 

 successive bands can be subdivided to any required degree of 

 accuracy. Wave-length is thus measured with extreme accuracy 

 by the amount of rotation of the plane of polarization. When 

 the apparatus is used, not with bright-line spectra but, with con- 

 tinuous spectra, the excessive loss of intensity by dispersion 

 which occurs in .ordinary speclrometers may be avoided. — Dr. 

 Wcodhead communicated a paper by Mr. G. Brook, entitled 

 " Preliminary Remarks on the Homologies of the Mesenteries in 

 Antipatharia and other Anthozoa. " After describing the arrange- 

 ment and musculature in the common shore anemone, Edivardsia, 

 Cerianthidae, in Alcyonaria, Madreporaria, Mr. Brook pointed 

 out that the Antipatharia are generally supposed to be degener- 

 ate forms, and to have lost a considerable number of the mesen- 

 teries that were present in their ancestors. Mr. Brook, who is 

 examining the Challenger collection of Antipatharia, has been 

 able to make sections of twenty-three species, from which he 

 jinds that the arrangement, number, and relative development of 

 the mesenteries cannot be explained in accordance with the 

 views current on the subject. With the exception of two pairs 

 of directives the mesenteries do not appear to show the 

 paired arrangement usually looked for. He gives the arrange- 

 ment of the mesenteries in Cladopathes (six mesenteries), Anti- 

 pathes (ten mesenteries), Leiopathes (twelve mesenteries), and 

 points out that the arrangement in these forms receives its 

 explanation by a comparison with the order in which the first 

 twelve mesenttrries are, according to Lacaze-Duthiers, developed 

 in Hexactinire. In Actinia and Sagartia the first twelve mesen- 

 teries are developed in pairs which are not adjoining mesen- 

 teries, but are situated one on each side of the stomodaeum. The 

 order in which they are developed in Sagartia bellis (and in 

 Actinia equiual) precisely corresponds with their relative length 

 in Leiopathes. The first pair to be developed are those corre- 

 sponding to the transverse mesenteries in Antipathidae ; next 

 follow the two pairs of directives, and afterwards the three pairs 

 which he has termed "secondary" in Antipathid?e. The 

 shortest mesenteries in Leiopathes are the last of the six pairs to 

 be developed in Sagartia. Evidently, then, the mesenteries 

 forming a pair are originally opposite mesenteries and not 

 adjacent ones. We thus have, in forms with an elongated stomo 

 daeum, a true bilateral symmetry. The two pairs of directives 

 limit an anterior and a posterior unpaired chamber. Between 

 these two the coelenteron may be imperfectly divided into any 

 number of paired lateral chambers. Oa this interpretation the 

 arrangement in Alcyonaria, Ediuardsia, Cerianthidae, Madracis, 

 &c., is also easily understood : all are modifications of one plan. 

 In the Hexactiniae the simple bilateralism is masked, but a care- 

 ful study of the c -der in which the mesenteries are developed 

 shows clearly how this is brought about In all types the 

 mesenteries of a pair are originally on opposite sides of the 

 stomodaeum. The two pairs of " directives " cojie to be cuijacent 

 mesenteries, for the Reason that no new mesenteries are ever 

 formed between them, and with a further development of 

 mesenteries they come to be pushed closer together. As is 

 clearly seen from Hertwig's figures of the embryonic condition 

 in Peachia, the other so-called "pairs" of primary mesenteries 

 are not pairs developmentally, as they consist of mesenteries of 

 different ages. They are called pairs because they are arranged 

 in couples, having the retractor muscles on their inner surfaces. 

 In Hexactiniae the further increase in the number of mesenteries 

 takes place in a modified way. Buds appear which are on 

 opposite sides of the stomodaeum between existing "pairs," but, 

 instead of giving rise to a single mesentery as before, each gives 

 rise to two, with the retractor muscles on their inner surfaces. 

 The general plan of development Mr. Brook considers to be as 

 follows. The mesenteries have a radiate arrangement in forms 

 with a round stomodaeum ; this arrangement becomes bilateral 

 by an elongation of the stomodaeum in one axis — the sagittal. In 

 this case the anterior and posterior pairs (directives) come to 



consist of adjoining mesenteries, whilst the intermediate pairs 

 consist of opposite mesenteries. So long as the folds of the body- 

 wall give rise to only one mesentery each, the simple bilateral 

 arrangement is retained, as in Cerianthidae (this refers to bilateral 

 arrangement of parts, irrespective of the outline of the polyp). 

 In case the mesenterial rudiments give rise (after the formation 

 of the first twelve mesenteries) lo two mesenteries instead of one, 

 the Hexactinian type is reached. In certain Madreporaria ^e.g. 

 Lophohelia, Mtissa, and Euphyllia) the radiate arrangement 

 aj)pears never to be lost. At any rate, according to Fowler and 

 Bourne, there are no mesenteries distinguishable from the others 

 as "directives," and there is a perfectly radiate symmetry. 

 Such a general plan of development is also found in Peripatus 

 and in Vertebrata. In Peripatus the blastopore becomes 

 elongated and closes in the centre, but its two extremities re- 

 main open as the mouth and anus. The mesoblastic somites 

 are formed in the region in which the blastopore has closed, and 

 these become more numerous as the two extremities become 

 more and more separated. At present, Mr. Brook is only able 

 to indicate the bearing of these views in outline. He hopes, 

 however, shortly to make a more detailed communication on the 

 subject. 



January 7. — Prof. Chrystal, Vice-President, in the chair. — At 

 the request of the Council of the Society, Prof. Tait gave an 

 address on the compressibility of water, salt-solutions, glass, 

 and mercury. His address was illustrated by experiments. 



^Paris. 

 Academy of Sciences, January 21. — M. Des Cloizeaux, 

 President, in the chair. — On a point in the question of homo- 

 geneous elastic plaques, by M. H. Resal. In this note the author 

 proposes to base the hypothesis relative to the expressions of the 

 tangential dilatations on a supposition of a more general character 

 than that hitherto assumed by geometricians. — On the Haematozoa 

 detected by M. Laveran in the blood of the inhabitants of marshy 

 districts, by M. Bouchard. Attention is called to the great im- 

 portance of the discovery made by M. Laveran ten years ago, 

 and now placed beyond all doubt, that marsh fevers are of para- 

 sitic character. They ofTer the first known example in man of 

 an animal parasitism in which the pathogenic agent appears to 

 be placed at the lowest scale of animal life. While most in- 

 fectious maladies in man and animals are due to vegetable 

 microbism, the most important and widespread infectious 

 disease in man is now shown to depend on animal microbism. 

 The parasite observed by M. Laveran in Algeria has since been 

 found in France, Corsica, Italy, Russia, Madagascar, Tonquin, 

 and America, and is identical with the organism more recently 

 detected by Marchiafava and Celli in the blood of people in- 

 habiting marshy districts. — On the elementary terms in the 

 co-ordinates of a planet, by M. Hugo Gylden. Supplementing 

 his recent coaimunication on this subject, the author here points 

 out that, the convergence of the terms in question being estab- 

 lished, their numerical valuer may be determined by the methods 

 proposed in the paper on the determination of the radius vector in 

 the absolute orbits of the planets inserted in the ^TJl^thly Notices 

 of the Royal Astronomical Society, London. — On the distribution 

 of the aqueous vapour in the atmosphere, by M. A. Crova. In 

 a previous note {Cotnptes rendus, cviii. p. 35) MM. Crova and 

 Houdaille communicated the results of th^ observations made 

 last August at Bedoin and on the summit of Mont Ventoux. 

 From those results M. Crova here deduces the mode of distribu- 

 tion of the aqueous vapours at various altituies. Although only 

 approximate, the calculations show how rapidly the quantity of 

 vapour must decrease with the increase of altitude. The quantity 

 itself also varies greatly from day to day, which is again ex- 

 plained by the fact that the vapours are mainly confined to the 

 lower atmospheric regions, which are most directly influenced by 

 meteorological phenomena. — Note on the new meridian of 

 France, communicated by the Minister of War. The Geodetic 

 Section of the Service Geographique de I'Armee concluded in 

 1888 the measurement of the angles for the new meridian 

 begun eighteen years ago. The present note embodies a sum- 

 mary report of the main results, from which it appears that the 

 meridian of Delambre and Mechain, useful in their day, can 

 no longer serve as a base for the triangulation of France, 

 or for further researches on the form of the globe. For 

 these purposes the new meridian offers all the necessary 

 elements except for the south-west region, where fresh measure- 

 ments are required to secure co aplete accu racy —Observat ion 



