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[February 17, 19 16 



will consider that less than justice has been done to 

 Forbes's classical Survey Memoir on the fauna and 

 flora of the British Isles. So far from " the three 

 southern subfloras of Forbes in place of being the 

 oldest, as he supposed," being now known to be the 

 most recent, the relatively high antiquity at least of 

 Forbes's Lusitanian flora has been confirmed by much 

 recent work on the natural history of Ireland and 

 western Britain. 



Some interesting observations on the physiology of 

 frogs are recorded by Messrs. A. T. Cameron and 

 T. I. Brownlee in the Quart. Joiirn. Exp. Physiol., 

 vol. ix., No. 3. It is well known that frogs will 

 endure prolonged submersion in water, efficient respira- 

 tory exchange going on through the skin. The authors 

 find that with Rana pipiens in Manitoba, the average 

 time for which the animal will live under water is 

 sixteen days, with an observed maximum of fifty-two 

 days. Death from too prolonged immersion is pre- 

 ceded by swelling, due partly to absorbed water, but 

 largely to accumulation of absorbed nitrogen. In 

 another paper these authors discuss the upper limit 

 of temperature compatible with life in the frog. They 

 had previously fixed the lower limit at approximately 

 I 25° C. below freezing point. They now find that 

 R. pipiens cannot live for more than a few days sub- 

 merged in water at i8° C, and that a few minutes' 

 endurance of a temperature of 35° proved fatal. In 

 damp air similar results were obtained, but the high- 

 limit temperature requires longer to cause death. The 

 internal temperature of the animals scarcely difl'ers 

 from that of the medium, and can evidently vary only 

 within the limits mentioned if life is to be maintained. 



To determine whether selection, or mutation, is the 

 more important agency in evolution. Prof. W. Castle 

 some time ago started a series of experiments with 

 hooded-rats, since these afforded him the single genetic 

 factor necessary for his investigation. A very careful 

 analysis of the data accorded him after breeding 33,249 

 rats, excluding those which formed the subject of 

 ■'control" experiments, seems to- demonstrate clearly 

 enough that " there is apparently no limit to the quan- 

 titative change which can be produced in the hooded 

 pattern by selection, short of its complete extinction 

 in the all-white, or all-black condition." This being 

 so, then "two foundation postulates of the mutation 

 theory are false, viz. : (i) that continuous, or graded 

 variations, are not concerned in evolution, and (2) that 

 selection of such variations, no matter how long con- 

 tinued, can effect no permanent or progressive racial 

 changes. Selection, as an agency in evolution, must 

 then be restored to the important place it held in 

 Darwin's estimation, an agency capable of producing 

 continuous and progressive racial changes." Prof. 

 Castle states his case with remarkable lucidity in the 

 Scientific Monthly for Januarj', numerous diagrams 

 contributing not a little to tlie value of this most 

 important summary. 



In Knowledge for January Mr. Aubrey Drev/ dis- 

 cusses some cytological problems raised by recent 

 cancer research. He first describes the "jelly method " 

 of in vitro staining of cells, devised by H. C. Ross. 

 An agar jelly is made, and to this sodium chloride, 

 NO. 2416, VOL. 96] 



sodium citrate, and citric acid are added in certain 

 proportions, and afterwards sodium bicarbonate and 

 Unna's polychrome methylene-blue in quantities vary- 

 ing with the cells to be examined. For use the mix- 

 ture is melted, and a drop or two placed on a slide and 

 allowed to set. A little of the material to be examined 

 is then placed on the jelly, covered with a cover- 

 glass, incubated if necessary, and examined- micro- 

 scopically. In this way cells, such as leucocytes, can 

 be seen dividing, and the changes in structure ob- 

 served. Certain substances are found to be necessary 

 for cell-division to take place, and are termed 

 "auxetics," others increase cellular movements, 

 "kinetics," and some of the latter increase the activity 

 of auxetics and are termed " augmentors." These 

 substances may play a part in cancer production. Thus 

 certain auxetics and kinetics will produce tumours on 

 injection into animals. Workers in pitch and tar are 

 liable to be affected with cancer, but it is only gas- 

 works pitch and not blast-furnace pitch which pre- 

 disposes to cancer. By the jelly method it has been 

 shown that gasworks pitch and tar contain both 

 auxetics and kinetics (augmentors), but the blast- 

 furnace products contain only traces of auxetics and 

 no kinetics. 



We have received a copy of the list of seeds of hardy 

 herbaceous plants and of trees and shrubs which for 

 the most part have ripened at Kew during the past 

 year. This annual publication, forming the first appendix 

 of the Kew Bulletin for 1916, is a welcome sign that 

 despite great difficulties owing to the depletion of the 

 garden staff, the true functions of a botanic garden 

 are being successfully carried on at Kew. 



The Journal of the Royal Horticultural Society for 

 December, 1915, contains an interesting and very well- 

 illustrated paper by Mr. G. Forrest on the flora of 

 north-western Yunnan. The plates are from Mr. 

 Forrest's own photographs, and include remarkably 

 beautiful studies of several of the peculiar species of 

 Primula found in this region. The Rhododendrons are 

 also represented by numerous species, several being 

 dwarf alpines, which form regular "heaths." 

 Of these R. prostratum grows up to an altitude of 

 16,000 ft. Many of the Rhododendrons were found 

 on pure limestone rocks, but whether ihey are really 

 growing with their roots in the limestone rocks or in 

 pockets of humus was not definitely determined. 



Coconut cultivation, though still a small industry 

 in Queensland, is rapidly extending. Hitherto it had 

 been supposed that copra from Queensland coconuts 

 did not contain enough oil to be "of commercial value, 

 but the examination of a sample of copra from these 

 nuts at the Imperial Institute has now established that 

 the oil content is normal and the copra of good quality, 

 and brokers state that shipments would be readily 

 saleable in this country at good prices. Before the 

 war the bulk of the copra shipped to Europe from 

 Ceylon, India, and elsewhere was crushed in Germany 

 and France. Urgent representations on Ihis subject 

 were made by the Imperial Institute on the outbn 

 of war to the oil-seed crushing firms in the Uni 

 Kingdom, some of which have now begun to v 

 copra, with the result that there is. a new and l; 



