March 30, 1899] 



NATURE 



525 



SOCIETIES AND ACADEMIES. 

 London. 

 Royal Society, March 9. — " On the Structure and Affin- 

 ities of Malonia fecliiiata, K. Br., with an Account of the 

 Geological History of the Matonineffi." By A. C. Seward, 

 F. R.S., University Lecturer in Botany, Cambridge. 



The genus Malonia has long been known as an isolated type 

 among existing ferns. It is represented by two species, M. 

 fectinata R. Brown and M. sarmoitosa Baker, both confined 

 to the Malayan region. Matonia has not hitherto been exaniined 

 anatomically, and its reference by several writers to an inter- 

 mediate position between the Cyatheacete and Gleicheniacea:, 

 is based on the structure of the sorus, which, in the small num- 

 bers of sporangia and in its circular form, resembles the latter 

 family, while the presence of an indusium and the position of 

 the annulus afford connecting links with Cyatheaceous ferns. 



In Matonia pectinata the frond has a characteristic pedate 

 habit, with numerous long pinUL-e having slightly falcate linear 

 segments, practically all of which appear to be fertile. The 

 sori are circular in form and indusiate, consisting of about 

 eight large sporangia with an oblique incomplete annulus. The 

 dichotomously branched rhizome, which grows on the surface of 

 the ground, is thickly covered with a felt of multicellular hairs, 

 and gives rise to long-stalked fronds from its upper face, and a 

 few wiry roots, which may arise from any part of the surface of 

 the stem. 



The material which rendered possible the investigation of the 

 anatomical structure was generously supplied by Mr. Shelford, 

 of the Sarawak Museum, Borneo. 



The stem is polystelic, and of the gamostelic type ; there may 

 be two annular steles, with the centre of the stem occupied by 

 ground-tissue, or in shorter branches of the rhizome a third 

 vascular strand may occupy the axial region. Each stele 

 consists of xylem tracheids and associated parenchyma, sur- 

 rounded by phloem composed of large sieve tubes, with 

 numerous sieve-plates on the lateral walls, and phloem paren- 

 chyma ; an endodermis and pericycle surround each stele, and in 

 the case of the annular steles these layers occur both internally 

 and externally. At the nodes the outer annular stele bends up into 

 the leaf-stalk, and a branch is given off also from the margin of 

 a gap formed in the inner annular stele ; the axial vascular 

 strand may or may not be in continuity with the meristele of 

 the leaf. The petiole is traversed by a single stele, similar in 

 shape to that of certain Cyatheaceous ferns. 



The most interesting feature in the structure of the pinnules 

 is the marked papillose form of the lower epidermal cells. The 

 roots have a triarch stele enclosed by a few layers of thick 

 brown sclerous cells. 



In structure Matonia pcf/ina/a presents points of agreement 

 with several families of ferns, on the whole approximating more 

 closely to the CyatheaceLi; than to any other family ; but the 

 peculiarities are such as to fully confirm the conclusion 

 previously drawn from external characters that Matonia should 

 be placed in a separate division of the Filices. 



In Matonia we have a survival of a family of ferns, now 

 confined to a few localities in Borneo and the Malay peninsula, 

 and represented by two living species, which in the Mezozoic 

 epoch had a wide geographical rage, being especially abundant 

 in the European area. 



" New Form of Light Mirrors." By A. Mallock. Communi- 

 cated by Lord Rayleigh. 



The author in this paper describes a new form of light mirror, 

 which he thinks may be useful in cases where extreme lightness 

 and good definition have to be combined. 



The mirrors are formed by stretching the thin films left on the 

 surface of water, after a few drops of a solution of pyroxyline in 

 amyl acetate have been allowed to spread there and evaporate, 

 over rings whose edges have been ground to a true plane. 



The contraction of the film in drying causes it to approach so 

 closely to the plane in which the edge of the ring lies, that when 

 used as a reflector, the definition is equal to that obtained from 

 a worked glass surface of the same area, at any rate until the 

 film is more than two and a half inches in diameter. 



A two-inch diameter mirror may be made weighing con- 

 siderably less than ten grains. 



The author found considerable trouble, not yet completely 

 overcome, in silvering the films ; but success in this matter 

 appears to depend entirely on securing extreme surface cleanli- 

 ness both of the films and silvering bath, the films being in this 



NO. 1535, VOL. 59] 



respect enormously more sensitive to surface ten.sion influences 

 ban glass. 



" On the Gastric Gland of MoUusca and Decapod Crustacea : 

 its Structure and Functions." By C. A. MacMunn, M.A., M.D. 

 Communicated by Dr M. Foster, Sec. R.S. 



In 18S3 the author communicated a paper to the Royal 

 Society in which he described a pigment occurring in the so- 

 called liver of Invertebrates, which from its resemblance to plant 

 chlorophyll he named entero-chlorophyll, and in the F/ii/o- 

 sophical Transactions (Part i., 1886), a further contribution was 

 published. 



In the present paper the histology of the gland is dealt with, 

 and additional observations made by means of the spectrophoto- 

 meter, and otherwise, are described. 



Great difficulties attend the preparation of the gland for 

 microscopical purposes ; the author has, however, succeeded m 

 getting very satisfactory sections by means of formol — 20 to 30 

 per cent.— followed by 95 per cent, alcohol, and embedding in 

 celloidin. The sections being stained by hiemalum, eosin, 

 mucicarmine, thionin, "Soudan III.," &c. Curves obtained 

 by means of the spectrophotometer show that entero-chlorophyll 

 and plant chlorophyll are not identical, but when the latter is 

 changed into the well-known " modified " form, the maxima 

 and minima correspond. From this and other data it appears 

 that entero-chlorophyll is food chlorophyll which has been acted 

 on by the digestive juices. A study of sections confirms this 

 view, as one can see the entero-chlorophyll actually within the 

 intestinal epithelium of Patella, Mylilus, &c., dissolved in a 

 fatty medium, and between these epithelial cells, leucocytes, 

 which carry it to the gastric gland and elsewhere, are seen 

 insinuating themselves. In addition to its other functions, the 

 gastric gland appears to be an organ of excretion. 



Physical Society, March 24.— Prof. Oliver Lodge, F.R.S., 

 President, in the chair.— Mr. W. R Cooper read a paper by 

 Mr. A. P. Trotter on the minor variations of the Clark cell. The 

 author describes a .series of experiments in which he compared 

 the E.M.F. of certain standard cells at frequent intervals from 

 July 1896 to February 1897, at Cape Town, where the tem- 

 perature of the double box containing the cells varied between 

 the limits 13° C. and 28° C. One cell was selected for com- 

 parison with all the others. No special precautions seem to 

 have been taken to keep the temperature of this selected cell 

 constant. The observed difterences between the E.M F. of the 

 respective cells rarely exceeded o-QCi, corresponding to about a 

 quarter of an inch on the slide-wire of the potentiometer. De- 

 tails as to the area of the slider-contact are not stated ; the read- 

 ings were generally taken to the fourth decimal, i.e. to one- 

 tenth of a millivolt, and occasionally to one-fourth of this. 

 Temperature was read to c-i°C. on a mercury thermometer 

 placed through a hole in the double box containing the cells — 

 not in the cells themselves. Mr. E. H. Griffiths said that the 

 paper appeared to have value only in so far as it showed that 

 Clark cells at Cape Town behaved in a manner that agreed with 

 common knowledge and general experience everywhere else. 

 Their variations depended upon shifts of temperature, and the 

 consequent changes in the degree of saturation of the liquid. 

 From his own experiments during seven years, upon forty-two 

 Clark cells, he had shown that if temperature was kept constant 

 to within o°oi C, the steadiness and uniformity of all the 

 E.M.F.s was most remarkable. They started with discrepancies, 

 but at the end of the time it was impossible to detect any dif- 

 ferences. It was of little use to put a thermometer .anywhere 

 but within the cells ; very slight changes of temperatiire 

 caused serious changes in the degree of saturation of the liquid. 

 The existence of the capricious lag of E M. F. behind temperature 

 precluded the possibility of formulating a temperature correction 

 for Clark cells. In the case of Callendar cells there was no lag ; 

 their E.M.F. varied slightly with temperature, by a definite 

 amount, which could be corrected by a coefficient. Mr. 

 W. R. Cooper said the method of comparison used by 

 the author was unsuitable, because to arrive at the 

 differences of E.M.F. necessitated the measurement of 

 the E.M.F. of each cell. The variations only amounted to a 

 few ten-thousandths of a volt. The length of potentiometer-wire 

 corresponding to a thousandth of a volt was only a quarter of an 

 inch ; under such conditions it would be difficult to ensure 

 accuracy. A method of opposition would have been preferable. 

 Mr. Cooper had found that Board of Trade cells only vary about 



