October io, 1895] 



NA TURE 



585 



the material did not allow of any developmental study of the 

 archegonia. The concentric biindle of the primary embryonic 

 stem shows an endodermal layer. On the whole the author 

 found in Datuca a complete agreement, in all essential features, 

 with Aiii^ioplcrh and Marntlia, as regards prolhallus, repro- 

 ductive organs, and embryo development. 



Physioi.oc.v, iS:c. 



The localisation, the transport and role of hydroycanic acid in 

 Pavgimii fdiilc, Reinw. , by Dr. M. Trcub (Huitenzorg, Java). — 

 Five years ago Dr. Greshoff made the remarkable discovery that 

 the poisonous sub.stance contained in great quantities in all the 

 jjarts of Pallidum ediilc, was nothing else than hydrocyanic acid. 

 This interesting chemical discovery was the starting-point of Dr. 

 Treub's physiological investigations. In microchemical re- 

 searches hydrocyanic acid presents a considerable advantage as 

 compared with the great majority of substances to be detected in 

 lis.sues by reagents ; namely, that the I'russian blue reaction, 

 easily applicable in inicr(jchemical research, gives comjiletely 

 iriistworlhy results. The appearance of Prussian blue in a cell 

 may be accepted as certain proof of the previous occurrence in the 

 cell of hydrocyanic acid, no other substance producing the same 

 reaction. The leaves prove to be the chief factories of hydro- 

 cyanic acid in Paiigiiiiii, though there are other much smaller 

 local factories of this substance in the tissues of other organs. 

 The hydrocyanic acid formed in the leaves is conducted through 

 the leaf-stalks to the stem, and distributed to the spots where 

 |ilastic material is wanted. The acid travels in the phloem of 

 ihe fibro-vascular bundles. Dr. Treub regards the hydro- 

 cyanic acid in Pangiinn cdule. as one of the first plastic 

 materials for building up proteids ; he thinks it is, in this plant, 

 the first detectalile, and perhaps the first formed product of 

 the assimilation of inorganic nitrogen. In accordance with this 

 hypothesis, the formation of hydrocyanic acid in Paitgitiin 

 depends, on the one hand, on the presence of carbo-hydrates 

 or analogous products of the carbon-assimilation, and, on the 

 other hand, on the presence of nitrates. These two points 

 were proved, or at least rendered acceptable, by a great number 

 of experiments made by Dr. Treub in the Buitenzorg Garden.s. 

 ('Ihe details of this investigation will be found ina paper appear- 

 ing in the forthcoming number of the Annates de iardiu 

 i'l'taiiiijite de Htiiteuzorg.) 



On the diurnal variation in the amount of diastase in foliage 

 leaves, by I'rof. Re\nolds Cireen, F.R.S. The diastase which 

 is present in foliage leaves varies in amount during the day, 

 l)eing greatest in the early morning, and lea.st after sunset. The 

 cause of the variation has been ascertained to be chiefly, if not 

 entirely, due to the action of the sunlight. The author showed 

 last year, at the Oxford meeting, that diastatic extracts exposed 

 to .sunlight or electric light, without the interposition of any 

 form of screen, have Iheir activity largely impaired, the damage 

 amounting sometimes to 70 per cent. Kxperiments made upon 

 the living leaf of the scarlet-runner showed a similar destruc- 

 tive action of the hght, the amount of destruction only 

 amounting, however, to about 10 to 20 per cent. The author 

 attributes this difference to the screening action of the proteids 

 in the cells of the leaf 



(-)n cross and self fertilisation, with special reference to pollen 

 pre])otency, by J. C. Willis. The time has passed for regarding 

 sell-fertilisation as being always necessarily harmful in itself, and 

 it is now recognised as a regular feature in the life-history of 

 many plant.s. There are many species of plants in which both 

 self and cross pollination occur nearly, or quite, simultaneously, 

 Mnd it is very desirable to know what hap])ens in these cases. 

 Darwin's experiments render it probable that prepotency of 

 foreign pollen is usual. The author's experiments have Ijeen 

 devoted to a .study of the relative chemical attraction of " own " 

 and " foreign" pollen by the same stigma (chiefly in gelatine and 

 .igar cultures), and have given negative results. It seems 

 probable, putting together all the various known facts, that jwe- 

 potency, where it occurs, is due to actions set up after the pollen 

 tubes have entered the stigma, these actions tending to favour 

 the growth of the " foreign " pollen-tubes, and to check that of 

 the "own" pollen. 



Pai..v;ohotany. 



The chief results of Williamson's work on the Carboniferous 

 I'lanls, by Dr. D. II. Scott, K.R.S. The origin and history of 

 the late I'rof. Williamson's lesearches on the Carboniferous flora 

 were btietly traced. His great work, chiefly, though not entirely, 



NO. 1354, VOL. 52] 



contained in his long series of memoirs in the Philosophical 

 Transactions of the Royal Society, consisted in thoroughly 

 elucidating the structure of British fos.sil plants of the Coal 

 period, and thus determining, on a sound basis, the main lines 



of their aflinitics. 



four of the principal types investigated by Williamson were 

 selected for illustration — the Calamarieic,\\ieSphenophyllea, the 

 Lyginodendreie , and the /.ycopodiaceic. 



(1) The Calamarieie. — Williamson's great aim, which he 

 kept in view all through, was to demonstrate the essential unity 

 of type of the British Calamites, i.e. that they are all Crypto- 

 gams, of equisetaceous affinities (though sometimes hetero- 

 sporous), but possessing precisely the same mode of growth in 

 thickness by means of a cambium, which is now characteristic 

 of Dicotyledons and (jynmosperms. His researches have given 

 us a fairly complete knowledge of the organisation of these 

 arborescent Horse-tails. 



(2) The Sphenophylleie, a remarkable group of vascular 

 Cryptogams, unrepresented among living plants, but having 

 certain characters in common both with Lycopodiaccic and 

 Et^itiseiaceic, are now very thoroughly known, owing, in a great 

 degree, to Williamson's investigations. The discovery of the 

 structure of the fructification, absolutely unique among Crypto- 

 gams, was in the first instance entirely his own. 



(3) The Lyginodendreie. — The existence of this family, which 

 consists of plants with the foliage of ferns, but with stems 

 and roots which recall those of Cycads, was revealed by 

 Williamson. This appears to be the most striking case of an 

 intermediate group yet found among fo.ssil plants. 



(4) The Lycopodiaceie. — Williamson added enormously to our 

 knowledge of this great family, and proved conclusively that 

 Sigillaria and Lepidodendron are essentialy similar in structure, 

 both genera, as well as their allies, being true Lycopodiaceous- 

 Cryptogams. but with secondary growth in almost all cases. He 

 demonstrated the relation between the vegetative organs and the 

 fructification in many of these plants, and by his researches on 

 Stigiiiarici,m?Li\\i known the structure of their subterranean parts. 

 The different types of Lepidodendron, of which he investigated 

 the structure, were so numerous, as to place our knowledge of 

 these plants on a broad and secure foundation. (The paper was 

 illustrated by lantern-slides, partly from Williamson's figures, 

 and partly original.) 



On a new form of fructification in Sphenophylliim, by (}ra 

 Solms-Laubach (Strassburg). ("Jraf Solms gave a brief .sketch 

 of the history of our knowledge tif the fructification of the 

 Carboniferous genus Sphcncphyllum. He described the type of 

 .St robilus originally named by 'VVilliamson Voliinannia Dawsoni, 

 and subseipiently placed by Weiss in the genus Jiowmanites ; 

 this fructification has recently been shown by Williamson and 

 Zeil'er to_ belong to Sphenopliyllum. The author proceeded to give 

 an account of a new form of strobilus recently obtained from rocks 

 of Culm age in .Sile.sia ; this shows certain important deviations 

 from the fructifications previously examined. In the Spheno- 

 piiytliim slrobili from the Coal- Measures the axis bears successive 

 verticils of coherent bracts, the sporangia are borne singly at the 

 end of long pedicels twice as numerous as the bracts, and arising 

 from the ujiper surface of the coherent disc near the axil. In the 

 Culm species, Splienopliyliiim A'cmeri. sp. nov. , the bracts of 

 successive whorls are superposed and not alternate, as described 

 by other writers, in the Coal-Measure species ; a more 

 important feature of the new form is the occurrence of two 

 sporangia instead of one on each sporangiophore or pedicel. 



In the cour.se of his remarks, Graf Solms referred to the 

 unique collection of microscopic preparations of fossil plants 

 left by Prof. Williamson : he emphasised in the strongest 

 terms the immense importance of the collection, and pointed out 

 how every worker in the field of Paleozoic botany must con- 

 stantly consult the invaluable type specimens in the William.son 

 cabinets. 



On English amber, by Dr. Conwentz (Danzig). The author of 

 this paper gave an account of the Baltic and English andier, and 

 its vegetable contents. .After describing the dift'erent forms of 

 Tertiary amber, he referred to the occurrence of .succinite on 

 the coasts of Es.sex, Sufi'olk, and Norfolk ; the specimens being 

 usually found with seaweed, thrown up by the tide.s. Occa- 

 sionally pieces have been met with weighing over two pounds. 

 Dr. Conwentz described the method of examining the plant 

 fragments enclosed in amber, and compared the manner of )>re- 

 servation with that of recent plant sections mounted in Canada 

 balsam. The amber was originally pouted out from the roots, 



