474 



NA TURE 



March 15, 1894 



landscape could only be indifferently represented on such a 

 coarse-grained structure, it would do very well for things near 

 enough to occupy a considerable part of the field of view. 



Linnean Society, February 15. — Prof. Stewart, President, 

 in the chair. — -Dr. Maxwell Masters exhibited a remarkably 

 good specimen of Pczha ttiberosa on root of Anemone. It is 

 only comparatively recently that the hard lumps (sclerotia) in 

 the soil of anemone beds have been definitely associated with 

 the fruit of this Peziza ; at one time the sclerotia were regarded 

 as diseased masses of the root-stock. Dr. Masters also exhi- 

 bited some root-galls on plum caused by Cyitips (Blorkiza) 

 dermiualis. Mr. Cameron, in his monograph on the CynipiJa, 

 published by the Royal Society, has noticed galls formed by 

 this insect on the beech, pine, and vine, but not on the plum. — 

 Mr. Digby Nicholl exhibited a singular variety of the partridge 

 iPerdix cinerecr), which had been shot by Mr. A. Waugh, near 

 Creswell, Northumberland, in September 1893. I" colour it 

 resembled the red grouse, having the breast and fl:\nks suffused 

 with large patches of dark reddish-brown, and the dorsal 

 (plumage very much darker than usual. Mr. Harling pointed 



NO. 1272, VOL. 49] 



out that this variety was described and figured by the late John 

 Hancock in his " Catalogue of the Birds of Northumberland," 

 where it had been met with more than twenty years ago, and in 

 which county he himself had also procured a specimen at Cor- 

 bridge-on-Tyne, which was preserved in the collection of 

 varieties formed by the late Mr. F. Bond. — Mr. Norman 

 Douglass exhibited a black variety of the water-vole, Arvicola 

 aniphihius, captured at Banchory, Kincardineshire ; remarking 

 that this vaiiety, which was at one time considered to be 

 restricted to Scotland, had been met with in several English 

 counties {Zoologist, 1892, pp. 281-293^ and was well established 

 in the fen country of Norfolk and Cambridgeshire. — Mr. 

 George Brebner read a paper on the origin of the filamentous 

 thallus o{ Ditmonlia filiformis, in which, by the aid of the oxy- 

 hydrogen lantern, he demonstraled (1) that D. Jilijormis has a 

 creeping basal thallus by which it adheres to the substratum ; 



(2) that the creeping thallus is perennial, and when epiphytic is 

 attached to its host by plugs of tissue which cause marked dis- 

 integration of the cells of the host ; (3) that the ordinary fili- 

 form thallus owes its origin to the intercalary transverse septa- 

 tion of the articulations of certain branches of the creeping 

 thallus. The group of active filaments may be endogenous or 

 exogenous, and the order in which the rows of cells became 

 specialised is generally centrifugal ; (4) these specialised out- 

 growths emerge from the creeping thallus — remaining attached 

 to it by the basal portion — and by the subsequent growth and 

 division of the constituent filaments give rise to the annual well 

 known Z^.yf///^;';;//.? thallus. The paper, which was listened 

 to with great interest, was criticised by Dr. D. H. Scott, Mr. 

 George Murray, and others. — On behalf of Mr. D. J, Scourfield, 

 a paper was communicated by Prof. Miall, on Entomostraca 

 and the surface-film of water. Briefly summarised, the principal 

 views advanced in this paper were the following : (i) To many 

 Entomostraca the surface film of water is a very dan:4erous ele- 

 ment in their environment ; to this category belong large num- 

 bers of the Cladocera and Ostracoda ; (2) to some other Ento- 

 mostraca, conversely, the surface film affirds peculiar advantages. 

 This class includes, so far as yet known, only a few specially 

 modified Cladocera and Ostracoda, and some Copepods, which 

 do not, however, present any apparent structural modifications ; 



(3) in all cases (except where some Copepods possibly make use 

 of the properties of the surface-film to attach themselves to 

 aquatic plants above the general water-level) the relation to the 

 surface-film, whether beneficial or the reverse, depends funda- 

 mentally upon the same physical principles, namely, the 

 upward pull of the surface-film when forming a capillary 

 depression, and the possession by the animals of water- 

 repellent shells, ridges, scales, or setse, capable of penetrating 

 iha surface-film, and producing capillary depressions. 



Geological Society, Feb. 21. - Dr. H. Woodward, F.R.S. 

 President, in the chair. — The following communications were 

 read : — On the relations of the basic and acid rocks of the Tertiary 

 volcanic series of the Inner Hebrides, by Sir Archibald Geikie, 

 F.R.S. After an introductory sketch of his connection with 

 the investigation of the Tertiary volcanic rocks of Britain, the 

 author proceeded to describe the structure of the ground at 

 the head of Glen Sligachan, Skye, which had recently been 

 cited by Prof. Judd as affording inclusions of Tertiary granite in 

 the gabbro, and as thus demonstrating that the latter was the 

 younger rock. He first showed that the gabbro, instead of 

 being one eruptive mass, consisted of numerous thin beds and 

 sills of different varieties of gabbro, some of which were in- 

 jected into the others. These various sheets, often admirably 

 banded, were seen to be truncated by the line of junction with 

 the great granophyre-tract of Glen Sligachan. A large mass of 

 coarse agglomerate was likewise cut off along the same line. 

 These structures were entirely opposed to the idea of the 

 gabbro being an eruptive mass which had broken through the 

 granophyre. They could only be accounted for, either by a 

 fault which had brought the two rocks together, or by the acid 

 rock having disrupted the basic. But there was ample evidence 

 that no fault occurred at the boundary-line. The granophyre 

 became fine-grained, felsitic, and spherulitic along its margin, 

 where it abutted against the complex mass of basic rocks. 

 These structures continued altogether independent of the vary- 

 ing distribution of the gabbros, and were seen even where the 

 granophyre ran along the side of the agglomerate. Similar 

 structures were of common occurrence along the margins of 

 the granophyre-bosses and sills of the Inner Hebrides, being 

 found not only next the gabbro, but next the Jurassic sand- 



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