334 



NA TURE 



[February 6, 1908 



(? assimilatory) of the nervo-ccntre induces an autonomic 

 ( ? dissimilatorv) excitation. 



Geological Society, January. 8.— Sir Archibald Geikie, 

 K.L.B., .Sec.R.S., president, in the chair.— Chronoloijv of 

 the Glacial epoch in North .America : Prof. G. F Wright 

 In the case of Plum Creek, Lorain County (Ohio) the 

 study of the activity of the stream and of the amount of 

 worl< done since the Glacial epoch has yielded important 

 results Ihis stream began erosion when the temporary 

 lake, held up by the ice, was maintained at the level of 

 Its i-ort Wayne outlet; it has never had anything more 

 resistant than Till to act upon. From a section 5000 feet 

 long It has excavated 34 million cubic feet of Boulder- 

 clay removing it from exposed banks 1600 feet long. 

 1 welve years erosion of a soo-feet length of a part of the 

 trough of the stream gives a rate of 8450 cubic feet per 

 annum Therefore, the removal of 34 million cubic feet 

 from the 5000-feet section would give a period of 2So< 



jr""';., r 'f 0";°''°"^ °f *^ Niagara Gorge began later 

 than that of Plum Creek, and dates from midway between 

 the disappearance of the ice from northern Ohio and from 

 yuebec. If conditions have been uniform, the age of the 

 gorge would be 7000 years. The author concludes with 

 some confidence, that the gorge is less than 10,000 years 

 old and that the ice of the Glacial epoch continued down 

 to that time to such an extent over the lower St. Lawrence 

 \ alley and Central New York that it obstructed the 

 eastern drainage of the Great Lakes.-The application of 

 quantitative methods to the study of the structure and 

 history of rocks : Dr. H. C. Sorby, F.R.S. The angle of 

 rest m the case of sand-grains of varving size and quality 

 enables the velocity of current necessary to keep such 

 sand drifting, and that needed to move it when at rest to 

 be ascertained approximately. The comparison of ihis 

 angle with that in sedimentary rocks made of similar 

 materials may be used to determine the vertical contrac- 

 tion of rocks since deposition, the average in cases studied 

 in lertiary and secondary rocks being from 100 to 57 

 I he connection between the structure of "ripple-drift" 

 and time is discussed. The connection between the struc- 

 tijre of a deposit and depth of water is found to be 

 ^'A^<\ i"^-""-^' q"^"t"atively. From the occurrence of 

 dnft-beddmg the depth of water may be determined to 

 within a few feet._ The deposition of fine deposits, like 

 « h- ;i,'"'T ^'^™.'''''"& J°. the amount of mud present and 

 whether the grains subside separately or cohere together 

 When no pressure is applied, the amount of water included 

 in the deposited clay may be 80 per cent., and when dry 

 the empty spaces may still amount to 32 per cent. Many 

 of the older rocks must now be only 20 per cent, of their 

 original thickness. In the green slates of Langdale the 

 volcanic eruptions sometimes occurred probably within a 

 few weeks of one another, and at other times at more 

 distant intervals. When deposited, part of the rock was 

 probably analogous to fine, loose sand, and part to semi- 

 liquid mud. In the Coal-measure sandstones deposition 

 at the rate of i inch per minute was common with 

 intervals of little or no deposit. The volume of invisible 

 rZ^T. '" ^^ ''''•"'' ^°"' ^q per cent, in some recent 

 rocks to nearly o in the ancient slates. The packine 

 of grains was discussed mathematically and experimentally 

 I he methods of determining the volume of minute cavities 

 in rocks were given. In some limestones the cavities have 

 been reduced by pressure to close on the mathematical 

 minimum, whereas m others the cavities are filled with 

 carbonate of lime. Some oolites have had their cavities 

 hllcd m a similar manner; in others most of the material 

 of the original grain has been removed, and the present 

 so idity ,s. due to the filling-up of the cavities mainly by 

 internal segregation. Among fine-grained rocks, ' the 

 Chalk probably was originally a sort of semi-liquid with 

 /o per cent, of water, and in its present state is about 

 45 per cent, of its original thickness ; the thickness of 

 some clays must have diminished still more. By the 

 measurement of green .spots in slates it can be deduced 

 I 1 t ro'^'^before cleavage was more consolidated than 

 rocks of the Caal-measures now are, and was then greatly 

 compressed The development of "slip-surfaces" in 

 '■'^^^^■-'■'■^ rocks IS great, and furnishes additional proof that 

 the cleavage is of mechanical origin. The' volume of 



NO. 1 997, VOL. ^'j'\ 



minute cavities in clay-rocks and their analogues of various 

 ages were discussed. There is a distinct relation between 

 it and the probable pressure to which the rocks have been 

 exposed. 



Zoological Society, January 14.— Prof. J. Rose Bradford, 

 F.R.S., vice-president, in the chair. — Mammals obtained 

 in the Shantung Peninsula, N. China, by Mr. M. P. 

 Anderson, for the Duke of Bedford's exploration of 

 eastern Asia : O. Thomas. No mammals had come from 

 this region since the time of Consul Swinhoe, who visited 

 it in 1866-8. The present series contained 106 specimens 

 belonging to six species, of which one was new. — The 

 musculature and other points in the anatomy of the 

 engystomatid frog Brcviceps verrucosus : F. E. Beddard. 

 — The hermaphroditism of the amphipod Orcliestia 

 deshayesii, Audouin : C. L. Bouleng^er. 



Linnean Society, January 16.— Prof. W. A. Herdman, 

 F.R.S., president, in the chair. — Stages of soil denuda- 

 tion and forest destruction in the Tyrol : A. P. Young. 

 Slides were shown from photographs taken in two valleys, 

 one north of the Brenner Pass, the Navistal, near Inns- 

 bruck, and one south of the pass, the Schalderertal, near 

 Brixen,_ illustrating various limits, commencing near the 

 upper limit of the vine cultivation at about 700 metres to 

 the snow limit at about 2800 metres. Great waste of soil 

 is caused in forest land by the simultaneous felling of tr.r- 

 over single plots of ground, and in the higher levels l.\ 

 the encroachments of grazing animals. One effect of tlii^ 

 waste is the recession, not only of the tree line, but al>.> 

 of the limit of continuous forests, which is generally cun- 

 sidered as distinct from the tree line. — Notes on Brassica 

 crosses: A. W. Sutton. The origin of some of the culti- 

 vated forms of Brassicas has been very obscure, and thi-i 

 has led to much confusion in their classification. It h:i^ 

 naturally been supposed that by careful study of tho^. 

 types which intercross with one another, and of thoM 

 which refuse to intercross, some light might be thrown 

 upon the origin of many Brassicas which to-day form su 

 important a portion of the plants used in agriculture and 

 horticulture. Consequently, experiments were undertaken 

 to investigate the tendency or otherwise to intercross. 

 Various accepted forms of Brassica oleracca (such as kale, 

 cabbage, savoy, and Brussels sprouts) were planted side bv 

 side and allowed to flower and seed. Result : — .\ lar^;' 

 collection of nondescript plants, some of which, after self r- 

 tion, have been practically fi.xed as new and useful types. 

 Some of the generally accepted types of Brassica oleracea 

 were arranged in " sets " together with types of Brassica 

 campestris, B. rapa, and B. napus, that is to say, swedes 

 with rapes, cabbages with turnips, &c., and these were 

 allowed to bloom in juxtaposition. Result: — Many hybrid 

 plants resulted from certain " sets " where natural cross- 

 fertilisation took place, and in other cases the pure 

 parental types were reproduced when no cross-fertilisation 

 occurred. The results were quite in accordance with what 

 experience led the author to expect. As in the preceding 

 experiments several types had been seeded together, the ex- 

 periments were repeated under carefully controlled con- 

 ditions in order to find by artificial cross-fertilisation to 

 which of the types the resulting hybrid forms were due. 

 .Artificial crosses (about eighty-six) w-ere attempted between 

 many of the different types of Brassicas. .As was expected, 

 many attempted crosses failed to produce hybrid forms, no 

 seed being developed, probably showing that in these cases 

 crossing was impossible. Other crosses gave seeds, in 

 some cases these being well developed, but in others small 

 and immature. These seeds when sown produced inter- 

 mediate or hybrid plants quite unlike the parental forms, 

 thus showing that cross-fertilisation was possible and had 

 occurred, confirming experience gained in the practical 

 work of seed-growing. — Revision of the genus Illigera, 

 Blumc : S. T. Dunn. 



^ Chemical Society. January 16.— Sir William Ramsay, 

 K.C.B., F.R.S., president, in the chair. — Colour and con- 

 stitution of azo-compounds, part ii., the salts of ^-hydroxv- 

 azo-compounds with mineral acids: J. J. Fox and J. 'i'. 

 Hewitt. The authors accept Tuck's statement that 

 benzeneazonaphtho! and its ethyl ether are similar in struc- 

 ture, but not his hypothesis that this structure is of the 



