Sept. 24, 1874] 



NATURE 



433 



without any intervening coal measures, for three-and-a-half 

 miles, when a small trough of the middle coal measures, with four 

 of the upjier Coalisland beds, rise up. This field is but two. 

 and-a-half miles long, and a quarter wide, and yet it must con- 

 tain the whole series of the middle and lower coal measures, the 

 millstone grit and Voredale beds. Here, the author calculates, 

 there are 800,000 tons of coal. The author proceeded to explain 

 when and how the two coal-fields became isolated from each 

 other ; and why, in the immediate vicinity of these coal measures, 

 the Permian rocks are found reposing directly on the limestone. 

 At the close of the carboniferous period the rocks were forced 

 into flexures, ranging east and west, owing to forces acting from 

 the northwards, as Prof. Hull shows acted in England. Denuda- 

 tion following, we had a set of plains, or edges of limestone, and 

 troughs of coal measures, all of which were overlapped by the 

 Permian and Trias. On subsequent denudation and post-triassic 

 faults occurring, some portions of the coal measures would be laid 

 bare or saved beneath the newer formations. As the whole dis- 

 trict is cut up by faults, and the rock exposures few, the evidences 

 of these flexures are obscure. 



SECTION D— Biology 

 Dei'artment of Zoology and Botany 



Dr. Williams read a paper On Specimens of Alga from Jersey. 

 The paper referred to the large number of species of marine 

 algiv to be found at Jersey, and to the favourable position of the 

 island for their development. Dr. Williams produced a splendid 

 collection of alga; preserved by a lady residing in Dublin. 



Prof Lawson read a paper On certain peculiarities in the In- 

 dian Ampeluieic. He remarked that many of the species were 

 climbers, with their branches interlacing in the tops of the 

 highest trees. In the stems of all were to be found numerous 

 very large ducts, »nd these ducts were filled with intra-cellular 

 vesicles, in which, at a certain time of year, abundance of starch 

 was developed. He also remarked that in the fruit most im- 

 portant differences might be found, but that these afforded no 

 means by which to divide the genus into natural sections. With 

 respect to the inflorescence, he said there was great variety of 

 form. Two species only reached the eastern coast of Africa, 

 most being confined to India, though some few were common 

 throughout the Malayan Archipelago. 



On the Growth of Tree-ferns, by D. Moore. — The general 

 conclusions arrived at in this paper were (i) Some of the kinds 

 of tree-ferns grow with greater rapidity and form their steins 

 in a much shorter period than is generally supposed to be the 

 case; (2) After they att«in a certain height the acrogenous buds 

 are formed much closer together, one above the other, than they 

 are lower down on the stem ; hence their elongation is much 

 slower ; (3) Some of the sorts which at first form short rhizo- 

 matous stems before they take an upright position require a 

 considerable number of years to perfect the early parts, but after 

 the stem has been formed and an upright position taken, the 

 growth is much quicker and the elongation advances rather 

 rapidly compared with it, while the stem remains in a rhizomatous 

 state. 



Mosses of the North of Ireland, by S. A. Stewart. — Turner, in 

 1804, enumerated as Irish 230 species of mosses ; Dr. Taylor, 

 in 1836, mentions about the same number; and Dr. D. Moore, 

 in 1S72, gives a list of 3S5 Irish species, to which the author of 

 the present paper adds four others, viz., 3S9, or more than two- 

 thirds of the British mosses. Thus, relatively to the British 

 Flora, Ireland has quite as large a proportion of mosses as she 

 has of flowering plants, proving that Irish muscology has not 

 been neglected. No separate lists of the mosses occurring in the 

 northern counties have been published ; but after consulting the 

 records of Dr. Taylor in the " Flora Ilibernica," and the valu- 

 able list of Irish mosses by Dr. Moore, also some detaclied 

 papers on the subject, the author ascertains that the number of 

 species occurring in the district amounts to 195, or more than 

 one-half of the Irish mosses. The district is defined to consist 

 of the counties of Down and Antrim, with a small portion of Co. 

 Deny, bordering on Antrim. The list includes a large number 

 of rare mosses. The following have not been previously re- 

 corded as Irish, viz. : — Fissidens inctuvis Schw. var. Lyiei, found 

 only on a greensand rock on the Black Mountain, near Belfast ; 

 Tayloria scrrata, in small quantity, near the summit of Ben- 

 bradagh Mountain, Co. Dcrry ; Muiiim sitb-^lobosum, in wet peat 

 bog on Cave Hill, near Belfast, and in a similar habitat on 



Carrickfergus Common ; Seligeria calcarea, on Black Mountain, 

 near Belfast, appearing like black specks on small lumps of 

 chalk in the grass. Mr. C. P. Ilobkirk, of Huddersfield, has 

 been kind enough to identify the specimens of the above-named 

 mosses. 



Prof Dickson exhibited specimens of an abnormal form of the 

 ox-eye daisy (Chrysanthemum hncanthemum), in which the 

 outer florets of the ray {normally ligulatc and female) exhibit an 

 irregularly tubular corolla, not very unlike that in tlie neuter 

 florets in certain Centaureas. Structurally these abnormal florets 

 are hermaphrodite, but appear always to be functionally neuter 

 or sterde. 



Mr. Bentham remarked that similarly abnormal tubular florets, 

 stracturally hermaphrodite, and functionally neuter, occur in 

 certain varieties of Chrysanthemum indicum and Dahlia. 



Mr. G. Bentham, F.R.S. read a report On the recent progress 

 and present state of Systematic Botany, commencing with a sum- 

 mary sketch of the state of science in 1830, when the natural 

 method of Jussieu was beginning to supersede the sexual system 

 of Linnxus;of its progress from that year to iSjg, when the 

 study of the general affinities of plants had entirely superseded 

 the classing them according to single organs ; and of the great 

 advance effected since 1859, owing to the explanation of afiinities 

 given by the adoption of the doctrine of evolution. After some 

 notes on the language to be preferred, systematic works were then 

 considered under the six several heads of 0? dines plantarum. 

 Genera plantarum. Species plantarum. Monographs, Floras, and 

 miscellaneous descriptions. Under each head the particulars re- 

 quired were specified, the principal recent works glanced over, 

 with a short mention of the chief desiderata now recommended 

 to the attention of systematic botanists. 



Prof. Thiselton Dyer referred to the paper as evidencing the 

 labour necessary to acquire a proficiency in the knowledge of 

 botany. Some people thought botanical study was a kind of 

 pastime, but the paper just read proved the contrary. 



Sir John Lubbock believed that mutatis mutandis a great deal 

 of what Mr. Bentham said with regard to systematic botany 

 would apply equally to zoology. 



Prof Dickson gave the results of his investigations on the em- 

 bryogeny of TropiColum peregruium and Tropuolum speeiosnm. 

 In these species the principal peculiarity consists in the constant 

 penetration of the carpellary tissue by the extra-seminal root- 

 process. In Tropieolnin majus the extra-seminal root-process 

 developed from the outer side of the base of the suspensor. 

 After perforating the seed-coat it becomes elongated, and finishes 

 its course in the cavity of the seed-vessel. In rare cases, however, 

 this process has been found to penetrate by its very extremity 

 the' carpellary tissue. In TropiToliiin peregrinum the extra- 

 seminal process penetrates the carpel alter having run in the 

 cavity of the seed-vessel half-way. In Tropisolum speciosum 

 this process dips into the carpel immediately after emerging from 

 the seed. Dr. Dickson remarked that some would be disposed 

 to look upon the abnormality in Tropceolum majus and the nor- 

 mal form in TiopLCohim peregrinum as forms representing «'hat 

 might be viewed as stages in the evolution of such a species as 

 Tropicolum speciosum from some form analogous to TropiColuin 

 majus. In regard to this. Dr. Dickson adversely criticised the 

 Darwinian hypothesis, as, in his opinion, inapplicable to the case 

 under consideration. 



Mr. A. W. Bennett read a paper On thefoim of pollen-grains 

 in reference to the fertilisation ofjlowers. He stated that although 

 not unfrequently a common form of pollen-grain runs through a 

 whole group of plants, yet more often the form is found to be 

 adapted to the requirements of the species, and varies even 

 within a small circle of alTinity. In those plants which are fer- 

 tilised by the agency of insects, there are three general modes in 

 w-hich the form of the grain is adapted for the purpose. We 

 have, firstly — and this is liy far the most common form— an 

 elliptical grain, with three or more longitudinal furrows, as in 

 Ranunculus ficaria, Aucul<a japonica, and Bryonia dioica ; 

 secondly, spherical or elliptical, and covered with spines, as in many 

 Composita;, Malvacea-, and Cucurbitacea; ; and, thirdly, where 

 they are attached together by threads or a viscid excretion, as in 

 Richardia .Ethiopica. In those jdants.on the contrary, wliich are 

 fertilised by the agency of the wind, as most grasses, the hazel, and 

 Populus balsamifra, tlie pollen Is almost perfectly spherical 

 and unfurnished with any fiirrows, and is generally, muieover, 

 very light and dry. The genus Viola supplies two very markedly 

 diff-rcnt f rms, in one of \\1 i.h, the section to which T. ..i/.'/.vc 

 and /' oJorata belong, the grains have the ordin.ny cllipii rl 



