July 13, 1916] 



NATURE 



415 



the velocity of sliding vanishes and rolling is 

 impossible. In three dimensions the velocity of com- 

 pression may vanish three times, so that before the 

 first period of compression is over a second one may 

 intervene. No matter how rough the bodies are, 

 sliding may not cease, and the solution often given of 

 impact between perfectly rough bodies may be inaccu- 

 rate. — H. Kennedy : The large ions and condensation 

 nuclei from flames. An examination is made of the 

 nature of the large ions and nuclei from flames, which 

 seem to be identical with those studied by Aitken and 

 occurring in the atmosphere. The rate of decay of 

 ionisation in the case of the large ions from flames 

 is found to be according to the law dq/dt=—Pq^, 

 where q is the charge of one sign per c.c. and /8 a 

 constant. The number of nuclei per c.c. was 

 measured by Aitken 's apparatus. It is found that the 

 nuclei disappear according to the law dn/dt— —yti-, 

 and the rate of disappearance seems to be the same 

 whether the nuclei are charged or uncharged. The 

 large ions carrj- multiple charges, and the value of 

 the charge depends on the circumstances of produc- 

 tion. The mobility of the large ion, so far as experi- 

 ment has gone, seems to be the same in all circum- 

 stances of production. The mobility must, therefore, 

 be independent of the charge. The formation of the 

 nucleus does not depend on the presence of the 

 charge. 



Edinburgh. 

 Royal Society, June 4. — Dr. J. Home, president, in 

 the chair. — Prof. A. A. Lawson : The prothallus of Tmesi- 

 pteris tannensis. Tmesipteris and the closely-related 

 Psilotum form a group the main interest of which 

 lies in their phylogenetic isolation. Both genera are 

 limited to the tropics and sub-tropics, Tmesipteris 

 being found in the South Sea Islands, Australia, New- 

 Zealand, and parts of Polynesia. With the exception 

 of certain important descriptions by Lang, our know- 

 ledge of the gametophytes and embryo of the Psilotaceae 

 may be regarded as a complete blank. Shortly after 

 his rrrival in Australia in 1913 Prof. Lawson learned 

 that both genera were to be found in great abundance 

 in the vicinity of Sydney. After careful search several 

 specimens of the prothallus of Tmesipteris and one 

 specimen of what is believed to be the prothallus of 

 Psilotum were discovered. The present paper con- 

 tained an account of the general features of these 

 prothalli, including descriptions of the antheridia and 

 the archegonia. Observations on the embryo were 

 also made, but a full account is reserved for a later 

 paper, when more material will have been obtained. 

 As regards the structure of the archegonium, which 

 bears no very striking resemblance to either Equisetum 

 or Lycopodium, one is inclined to regard it as reduced. 

 This is not surprising in a plant the sf)orophyte and 

 gametophyte of which are both reduced and highly 

 specialised in their adaptation to definite habitats. — 

 Prof. E. T. Whittaker : On the theory of continued 

 fractions. The paper gave a general process for ex- 

 pressing a continued fraction as a continuant, and 

 showed how to express the differential coefficient of 

 a continued fraction as the ratio of two determinants 

 the constituents of which are definite functions of the 

 terms of the continued fraction. 



June 19. — Sir T. R. Eraser, vice-president, in the 

 chair. — Prof. C. R. Marshall : The pharmacological 

 action of nitric esters. The paper dealt mainly with 

 the relation between the chemical constitution and 

 pharmacological action of these esters. All that were 

 investigated, except those of organic acids and their 

 alkyl esters, caused dilatation of the blood-vessels. 

 The quantitative effect of the fully nitrated esters of 



NO. 2437, VOL. 97] 



the polyhydric alcohols and the sugars was chiefly 

 dependent on their solubility in aqueous media ; that 

 of nitric esters of monohydric alcohols was much less 

 dependent on this property. The influence of different 

 groupings was described, and the theory th^t the 

 pharmacological action of nitric esters is wholly due 

 to their reduction to nitrites was combated. Evidence 

 of the formation of nitric oxide haemoglobin was not 

 obtained. — C. W. Tyrrell : On the petrography of the 

 trachytic and allied rocks of the Carboniferous age 

 in the Clyde lava plateaux. These rocks were shown 

 to fall into four groups, viz. : (o) Albite Bostonites, A. 

 Trachytes, and A. Keratophyres ; (b) Bostonites, 

 Trachytes, and Keratophyres ; (c) Quartz Kerato- 

 phyres and Felsites ; (d) Phonolites. 



New South Wales. 



Linnean Society, April 26. — Mr. C. Hedley, vice 

 president, in the chair. — G. I. Playfair : Oocystis and 

 Eremosphaera (Algae). The object of this paper is 

 threefold : — (i) To give an account of all forms of 

 Oocystis and Eremosphaera met with in New South 

 Wales; (2) to direct attention to the polymorphism of 

 Eremosphaera, and to its connection with Oocystis; 

 (3) to supply the original descriptions and figures, so 

 far as possible, of all published species and forms of 

 the two genera. — Dr. J. M. Petrie : The chemical 

 investigation of some poisonous plants in the N.O. 

 Solanaceae. Part ii. — Nicotiana suaveolens, and the 

 identification of its alkaloid. JV. suaveolens is the 

 "native tobacco" of Australia, and the only endemic 

 species. It is a troublesome weed in the stock country, 

 sometimes referred to as poisonous, at other times as 

 a good fodder-plant, readily eaten by stock. As only 

 a very few among the eighty described species of 

 Nicotiana are known to contain nicotine, the author 

 examined plants from three different localities in the 

 interior of New South Wales, and in all identified and 

 proved the presence of nicotine. The amounts found 

 were 0035, 0003, 0004 per cent, of the fresh plants, 

 or 0-124, 001 1, 0015 per cent, of dried (at 100°) 

 plants. It was calculated from the lowest figxire 

 stated that enough alkaloid is contained in half a 

 pound of green plant to poison an ordinary-sized 

 sheep. — ^A. A, Hamilton : The instability of leaf- 

 morphology in relation to taxonomic botany. The 

 principal factors affecting leaf-morphology are tabu- 

 lated, and a summary of the more important altera- 

 tions resultant from their agency are given. -\ series 

 of examples (chiefly Australian) is submitted, illustrat- 

 ing the effect of environment on leaf-structure; and 

 evidence is offered, in certain cases, demonstrating the 

 development of heterogeny in the foliage of closely 

 allied plants, using dissimilar contrivances as protec- 

 tive agencies against adverse conditions ; and homo- 

 plasy in plants distantly related, but employing a 

 common protective device. — ^J. H. Maiden : Br achy- 

 chiton populneo-acerifolius, F. v. M., the crimson- 

 flowered Kurrajong. The name was applied by the 

 late Baron von Mueller to a tree, recognised as a 

 hybrid between B. acerifoUtis and B. populneus, grow- 

 ing in a garden at Mulgoa. Plants of the parent 

 species were then growing in the garden, but it was 

 I not certain that the hybrid had not been introduced as 

 I a seedling from elsewhere. Inquiries for similar 

 } plants have been widely circulated, and records are 

 ! now given of examples growing in different localities; 

 ' but, except in one instance, they are all cultivated 

 I plants, the historv of which is unknown. — J. H. 

 Maiden : A Eucaly'pt hybrid (Eucalyptus calophyllaX 

 \ E. ficifolid). E. cahphylla has white or creamy fila- 

 I ments, and E. -ficifolia bright scarlet. Plants of a 



