27« 



NATURE 



[December 5, 1918 



be developed, ["he more extensive use of moulded 

 blanks for lenses and prisms was advocated, and the 

 methods of moulding (or pressing) glass were 

 described. Types ol optical coi I uction were shown, 

 and it was suggested that "a three-piece cemented 

 objective appeared to give a more brilliant image than 

 those of the usual two pieces" construction, while, 

 owing to the flattei curves, it was probably but little 

 more expensive to produce. Various methods ol ad- 

 justment wnc described suitable for use where 

 instruments arc, and where they arc not, available. 

 Finally, various methods of testing definite and light 

 transmission were shown, including methods for the 

 rapid comparison of binoculars with a measured 

 standard. 



Zoological Society. November i<). Dr. A. Smith- 

 Woodward, vice-president, in the chair. Miss K. 

 Lander ; Method ol preparing skeletons In the use 

 of trypsin. A number of successful examples from 

 the society's prosectorium were exhibited. — E. Hatschek ; 

 I he forms assumed by drops and vortices of gelatin 

 in various coagulants. A series of the formations was 

 shown which simulated animal structures, and the 

 author demonstrated the method by which he obtained 

 his results. — Prof. F. Wood-Jones :' A cast and a set of 

 Rontgen-ray photographs taken from a chimpanzee 

 belonging to the society. The animal had recently 

 died from pulmonary tuberculosis, and attention was 

 directed to the possibility of diagnosing tubercle in 

 living subjects by die method described. — Dr. D. M. S. 

 Watson : Seymouria, the most primitive known 

 reptile. 



Royal Microscopical Society, November 20. Mr. |. E. 

 Barnard, president, in the chair.^R. Paulson and Miss 

 A. Lorrain Smith : Paper on microscopic preparations 

 which were mounted during an investigation, in colla- 

 boration with Somerville Hastings, respecting the 

 actual penetration of the living algal cells (gonidia) 

 of a lichen by the fungal hyphae. Reference was 

 made to the papers of Schneider, Elenkin, Elfving, 

 and Danilor in order to show that there was no agree- 

 ment regarding the details of the penetration ob- 

 served. Methods of fixing, staining, and mounting 

 were explained. Bonnev's was found most useful 

 for differentiating alga and fungus, and for showing 

 the various structures of the algal cell as the 

 chromatophore, the so-called pyrenoid, and an eccen- 

 tric body. Some slides illustrated the method by 

 which gonidia increase in number, numerous 

 daughter gonidia being shown within the mother- 

 cells. The average diameter of gonidia was 1:11, and 

 that of hyphae 3/1 to 4/1. During the whole pro- 

 gress of the work no clear case of penetration, and 

 very few doubtful cases, .were observed. Penetration 

 of the living gonidia by fungal hyphae occur so 

 seldom thai a theorv of parasitism based upon its 

 occurrence has verj little evidence to support it. 



Geological Society, November 20. — Mr. G. W. 

 Lamplugh, president, in the chair. — R. IT. Worth: 

 The geolog\ of the Meldon valleys, near Okehampton, 

 on the northern verge of Dartmoor. The area dealt 

 with lies between the London and South-Western 

 main railway line, from a point a little east of Meldon 

 viaduct lo near Sourton, and the ridge of Dartmoor 

 occupied by Black Tor, High YVilhavs, Yes Tor, and 

 West Mill Tor, 1" ing the greater part of the valley 

 of the Redaven and a portion of the valley of the 

 ■\Yest Okement. The southern extreme of this area 

 is occupied by the Dartmoor granite, north of which 

 are shales, in which occurs a patch of limestone, and 

 these are intersected by numerous bands of igneous 

 rock. The shales as a whole, with but slight local 

 deviations, strike north-east and south-west and dip 



NO. 2562, VOL. I02] 



north-westwards, the mean angle of dip being about 

 50 . I 1h sedimentary rocks are divisible into: — 



( i I An alumino-ai enaceous series, extending from the 



granite northwards for a breadth of somewhat moo 



than ball a mile; (2) a calcareous series, abruptly but 

 conformably succeeding the first; (3) a limestone, which 

 01 1 ins a short distance south of the railway ; (4) radio- 

 larian cherts a little above and a little below the 

 horizon of the limestone; and (5) an aluminous bed 

 north of the railway. In the sedimentary series pi 

 of weakness have developed, the surface-traces of 

 which are broadly coincident with the strike, but 

 which frequently lie counter to tin- dip. These planes 

 hoe been more or less successfully invaded by at 

 leasl three series of igneous rocks, the order of which, 

 commencing with the earliest, is as follows : — (a) \ 

 felsite with phenocrysts of micropegmatite, and quartz 

 which shows good rhombohedral cleavage. (b) A 

 series called the "dark igneous rocks." (c) Grani- 

 toid veins, subdivided into (1) the Meldon aplite and 

 its associates, and (2) fine-grained granites of the 

 ordinar) Dartmoor type. 



I.innean Society. November 21. Sir David Prain, 

 president, in the chair.— E. S. (ioodrich : A fatherless 

 frog, with remarks on artificial parthenogenesis. The 

 author remarked on the artificial development of 

 echinoderm eggs by special treatment into living 

 examples, and that it had been found that frogs' eggs 

 could follow a similar course. A female- frog, care- 

 fully prepared to guard against previous impregnation, 

 was employed, the eggs obtained by dissection were 

 placed in rows upon glass slips, and punctured by 

 fine glass needles of microscopic tenuity; blood was 

 then applied, and the treated eggs placed in water. 

 A certain number developed into tadpoles, and a few 

 into complete frogs. It was found that the leucocytes 

 in the blood were essential ; the serum or ordinary 

 red corpuscles were use less — Miss Muriel Bristol : A 

 review of the genus Chlorochytrium, Colin. From 

 investigations it appeared certain that the genera 

 Chlorocystis, Reinh. ; Stomatochytrium, Cunn. ; Enelo- 

 sphaera, Klebs ; Scotinosphaera, Klebs ; and Centro- 

 sphaera, Borzi, were slight variations of Cohn's genus. 

 Thirteen species were characterised in detail, and three 

 doubtful species of Schroeter were mentioned.- A. S. 

 Kennard and B. B. Woodward : The Linnean species 

 of non-marine mollusca that are represented in the 

 British fauna, with notes on the specimens of these 

 and other British forms in the Linnean collection. 

 There now seems some chance of approximate finality 

 being attainable in the matter of nomenclature on the 

 basis of priority — at least, in the case of the British 

 post-Pliocene non-marine mollusca, with which the 

 authors are particularly concerned. Accordingly, they 

 an- attempting a more thorough re vision of their 

 synonymy than was essayed by them in too; {Journ. 

 of Conch., vol. X., pp. 352-67) and 1.114 ("List of the- 

 British Non-Marine Mollusca," 8vo, pp. 12). 



Manchester. 

 Literary and Philosophical Society, November 12 Mr. 

 W. Thomson, president, in the chair. — Capt. D. M. S. 

 Watson : Biology and war. After referring to the us. of 

 much of the theon of natural selection in tin apologic - 

 for militarism, and pointing out the confusion always 

 prese 111 in the minds of those- who so use- it, the 

 speaker referred verv brieflv to the various types of 

 evolutionary changes exhibited by phylitic series of 

 animals known from palaeontological evidence, and 

 pointed out that such evidence of this kind as is avail- 

 able suggests thai natural -.lection has played onlv a 

 very limited part in the actual progress which has 

 occurred in animal structure. 



