126 



NATURE 



[February 6, 1908 



and south-eastern counties of England the species, it 

 appears, became rare during the first half of last century, 

 and in most of these it was exterminated before i860, 

 although isolated occurrences have been recorded since 

 that date in Hertfordshire, Surrey, and Sussex. In 

 Lincoln, Norfolk, and Suffolk it survived until the 'eighties, 

 and there have been recent occurrences in Leicestershire. 

 The Lake District and the west of north and central 

 Wales are, however, at present the sole strong-holds of 

 the species. Many of the isolated occurrences appear to 

 be due to the remarkable degree to which the marten 

 wanders. 



In addition to the well-known fishery of the pearl- 

 ovstcr, Cevlon, it appears from an article by Dr. A. Willey 

 in Spolia Zeylaitica for November, 1907, possesses a source 

 of pearl in beds of the " window-pane oyster " {Placuna 

 placenta) in the backwaters of the eastern province. These 

 beds occur in the backwaters of two neighbouring divisions 

 of the Trincomali district, one of which includes Lake 

 Tamblegam, the headquarters of the Placuna fishes. As 

 the lease of this fishery recently expired, Mr. Willey was 

 sent to the district to report on the best means of improving 

 the product of oysters. These molluscs, it seems, are 

 liable to be destroyed in large numbers by unusually 

 heavy falls of rain such as took place a year ago ; never- 

 theless, the species Is in the main a hardy creature, 

 capable of living for several hours out of water, and of 

 surviving for long periods in earthenware vessels if the 

 water be from time to time changed. No mention is made 

 by the author of the annual value of the pearls yielded 

 by the Placuna fishery. The paper includes an account of 

 cysticercoid larvae found parasitic in these oysters. 



Mr. W. Taliew contributes to the BuUetin dii Jardin 

 Imperial Botanique (vol. vii., part iii.), St. Petersburg, a 

 paper on the distribution of forests in the district of 

 Starobjelsk, which furnishes evidence that the " steppes " 

 were formerly wooded areas. Mr. A. A. .Sapehin discusses 

 the method by which water is absorbed by the sacs in such 

 liverworts as Frullania. 



LiEUT.-CoLONEL F. Bailey and Mr. R. C. M. Ferguson 

 both contribute articles to the Transactions of the Scottish 

 Arboricultural Society (vol. xx., part i.) on the Interlievei 

 State forest. The purchase by Government of this estatt 

 in Argyllshire affords great satisfaction to British foresters, 

 but it is hoped that it is only the first step in the policy 

 of acquisition by the State of land for afforestation pur- 

 poses. The estate, consisting of 12,000 acres, carries very 

 little timber, so that while it affords an opportunity for 

 showing how timber crops can be scientificially grown and 

 for recording data, it will not for many years provide a 

 demonstration forest. It is urged that two wooded areas 

 should be acquired for this purpose, one in the lowlands 

 where hardwoods are cultivated, and one in the highlands 

 stocked with conifers. 



It is a debated question whether it is preferable foi 

 science students to undertake practical experiments with 

 instruments of their own construction or to make use of 

 apparatus manufactured by instrument makers. Prof. 

 F. W. Ganong, formerly an advocate of the former 

 method in botanical physiology, now declares in favour of 

 instruments of greater precision, and with this purpose 

 has designed several pieces of apparatus that are being 

 manufactured by Messrs. Bausch and Lomb ; a descriptive 

 catalogue can be obtained from their agents in London, 

 Messrs. Staley and Co., Thavics Inn. Among the instru- 

 ments are a transpiration balance, clinostat, autographic 

 NO. 199;, VOL. 77] 



transpirometer, leaf-area cutter and leaf clasp, but the 

 photosynthometer and respirometer will probably be found 

 the most useful on account of the functions they record. 



A BATCH of pamphlets issued from the Royal Botanic 

 Gardens, Ceylon, as Nos. 2 to 5 of vol. iv. of the Circulars 

 and Agricultural Journal, has been received. Mr. E. B. 

 Denham, writing on the use and objects of agricultural 

 societies, attaches much importance to the visits of 

 travelling instructors and to the distribution of leaflets 

 printed in the vernacular ; also he suggests that the local 

 societies should make it their business to collect agri- 

 cultural data. In connection with camphor production, 

 Mr. J. K. Nock has prepared a useful circular on pro- 

 pagation. Practical hints are given for preparing the 

 seed beds and raising the seedlings. If good seed is not 

 obtainable, it is recommended to propagate by means of 

 root cuttings. The chief object of a circular by Mr. T. 

 Fetch is to direct attention to a stem disease caused by 

 the ascus-bearing fungus Alassaria theicola. The hyphae 

 of the fungus fill up the vessels of the wood and cut off 

 the supply of water and salts. The disease can be traced 

 by the discoloration of the wood. A catalogue of plants 

 available for distribution from the gardens has been pre- 

 pared by the curator, Mr. H. F. Macmillan. The 

 economic list comprises certain spice, rubber, fibre, and 

 drug plants. 



We have received the first number of the Quarterly 

 Journal of Experimental Physiology, a new periodical 

 issued under the editorship of Profs. Schafer, Gotch, Halli- 

 burton, Sherrington, Starling, and Dr. Waller. The four 

 papers contained in it maintain a high standard ; they 

 are : — (i) on the time taken in transmission of reflex 

 impulses in the spinal cord of the frog, by Florence 

 Buchanan ; (2) some comparisons between reflex inhibition 

 and refle.x excitation, by C. S. Sherrington ; (3) the 

 freezing of frog's nerve, with special reference to its 

 fatigability, by John Tait ; and (4) on protagon, by R. A. 

 Wilson and W. Cramer. We could have wished that it 

 had been possible to avoid the issue of a new journal, but 

 with so distinguished an editorial committee we presume 

 its appearance is necessary for the advancement of physio- 

 logical science. • 



In the third report to the Gas Engine Research Com- 

 mittee, presented to the Institution of Mechanical Engineers 

 on January 17 by Prof. F. W. Burstall, the results were 

 given of an interesting series of experiments carried out 

 during the past two years on an adapted form of one of 

 the Premier Company's existing types of gas-engine. The 

 engine employed was capable of giving 150 horse-power at 

 a speed of 170 revolutions per minute, the size of the 

 cylinder being 20 inches in diameter with a 24-inch stroke. 

 The diameter of the cylinder was reduced to 16 inches, 

 and an entirely new breech end was constructed with the 

 admission and exhaust valves horizontal. The tests were 

 undertaken to determine the thermal efficiencies based on 

 the indicated horse-power at various compressions, having 

 regard to the richness of the mixture, and to formulate, if 

 possible, the law connecting efficiency and compression. 

 The results of the experiments appear to show that the 

 most economical mean pressure is very considerably below 

 the maximum that can be obtained, and that the highest 

 economies arc obtained with a comparatively low maximum 

 temperature. Both these conclusions imply that the engine 

 should not only be subjected to lower pressure, but to 

 lower temperatures as well, and thus many of the difficul- 

 ties that arise in large engines from rich charges might 

 be avoided, and the maximum pressures kept down to quite 



