3o6 



NA TURE 



\Fcb. 1 8, 1875 



instructive as it is interesting to all who take the oppor- 

 tunity of glancing at it. There is a routine about educa- 

 tional works which is rarely diverged from to any consi- 

 derable extent. Beyond the information they contain 

 tht-re is always a mass of oral tradition, glimpses into 

 which only occasionally appear in print. This becomes, 

 in many cases, the basis of the higher work of the suc- 

 ceeding generation, and to the student it is an invalu- 

 able adjunct to his more formal reading. In the small 

 book before us, Prof. Newton has touched upon some 

 of these less familiar points, bringing to the foreground 

 several questions, the importance of which in the general 

 economy of nature is scarcely sufficiently appreciated. 

 He commences by a most instructive analogy, comparing 

 the cifferent members of the animal kingdom to a mixed 

 collection of coirs in a bag, whose history is to be deter- 

 mined mostly from what is to be found on their surfaces. 

 Some, like fossil forms, are no longer current ; in other 

 words, they are extinct. Others, in their stamping give 

 indications of the histories of the nations by which they 

 were struck, as do organised forms by their external 

 shape and internal structure ; and so on. Upon this 

 basis the principles of classification are, on an evolutionary 

 foundation, established in a most lucid manner. An 

 anecdote, particularly to the point, shows the fallacious 

 reasoning into which students are likely to fall when they 

 lay too little stress on the accuracy of the most minute 

 facts, the mistake of a distinguished French naturalist 

 with regard to the habits of the swallows found at Rouen 

 being the instance given. The section on Geographical 

 Distribution, when read in connection with the small map 

 which is introduced, is as definite and precise as can be 

 desired ; at the same time that the observations on the 

 effects of peculiarities in the- physical conditions of life 

 on the organisation of species have a bearing the full 

 significance of which Prof Newton has done so much to 

 indicate. The remarks on nomenclature will also be 

 fully assented to by all working naturalists. One of the 

 chapters is devoted to a rapid sketch of the different 

 classes of the animal kingdom ; and this, when taken in 

 connection with those on the subjects above mentioned, 

 makes the little volume as complete an introduction as 

 can be desired to the science of which it treats. 



LETTERS TO THE EDITOR 



[ The Editor does not hold himself responsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, 

 or to correspond with the writers cf, rejected manuscripts. 

 No notice is taken oj anonymous communications.'[ 



Marine Boulder Clay, and other Deposits 

 It seems from the concluding paragraphs of the report of the 

 C/«j//<'«^v/- Observations in NATURE, Vol. xi. p. 116, that the 

 dredge has at length settled the question of the mode of deposi- 

 tion of marine boulder clay, and shown that in the Southern 

 Ocean it is now being formed over areas perhaps as great as 

 those now covered «ith similar deposits in the northern hemi- 

 sphere. The facts stated show (i) The deposition of a bed of 

 mud and sand with fragments of stones from floating ice ; 

 (2) That this deposit is so rapid as completely lo mask or super- 

 sede the ordinary deposition of organic slime ; and (3) That in 

 certain areas of deep water there is a possibiUty that an excess 

 of carbonic atid may remove all trace of calcareous organisms. 

 It is further to be observed that, owing to the small amount of 

 land, the conditions are probably much less favourable than those 

 which existed in the north at the time ol the great Post-pliocene 

 subsidence. 



These facts appear to me to confirm the conclusion which I 

 have so often stated with reference to the boulder clay or " till " 

 of North America, and which I have endeavoured to establish 

 by the nature of the deposits now taking place in the areas of 

 ice-drift on the coast of North America, by the distribution and 

 chemical characters of the boulder-clay itself, and by the occur- 

 rence of marine fossils in it. It is to be hoped that in future we 

 shall not have so confident assertion as heretofore, that these 



remarkable clays are due to the action of land ice, and that they 

 will cease to be regarded as affording evidence of a " contmental 

 ice-cap " in temperate latitudes. 



The details given in the same communication with reference 

 to the formation of a "red clay" from the decomposition of 

 organic ooze, in connection with the remarks of Prof. William- 

 son in Nature, vol. xi. p. 148, are also very suggestive. They 

 help to account not merely for certain red clays and slates and 

 beds of silicious organisms, but also for the association of glau- 

 conite and other hydrous silicates with organic marine beds of all 

 ages ; an association which I have long held to be not accidental, 

 though its precise chemical conditions may be obscure. The 

 time may not be distant when geologists may learn to regard 

 many deposits of this kind, from the Serpentine, Loganite, and 

 similar minerals of the Laurentian up to the Modern Greensands, 

 as products connected with the animal life of the sea, or depen- 

 dent on it for their accumulation. Some chemical suggestions 

 bearing on this will be found in Dr. Sterry Hunt's recent volume 

 of "Chemical and Geological Essays," which I would commend 

 to the study of all your younger geologists. 



McGill College, Jan. 20 J. W. Dawson 



The Transit of Venus 



Among the brief telegraphic accounts given in Nature, vol. 

 xi. p. 122, of the work done by the several Transit expeditions, 

 is one from Janssen, in which it is stated that Venus was seen 

 over the sun's corona before contact (which contact, external or 

 internal, is unfortunately not mentioned). 



The idea of the rim of light round the planet being due to the 

 corona does not seem to have struck other observers ; and there 

 are one or two points, gathered 

 from my own observations, for 

 and against the conclusion, that 

 I may perhaps be pardoned for 

 bringing forward. 



For the coronal view, then. I 

 looked for, but failed to see, the 

 retreating edge ol the planet after 

 last external contact. The air, 

 however, was less steady than in 

 the morning, and my eye was 

 very weary with straining at the 

 last tiny indentation made by 

 Venus on the sun's iimb. 



Against the theory there are 

 the facts that the line of light 

 was apparently of equal thickness 

 throughout, and at half immer- 

 sion was visible up to the sun's 

 limb without perceptible loss of 

 light ; that at first internal con- 

 tact, or rather when the cusps 

 had almost united and the solar 

 light was but little cut off (Tide 

 A in diagram), the last portion 

 of the ring was undiminished in 

 brightness. Finally, in the pencil 

 notes taken at the time, I find, 

 referring to the ring of light, 

 these words : "A brighter spot 

 on lower limb, entering sun about 

 I immersion " (vide B). This 

 spot I then imagined to be due 

 to a portion of the planet iry 



atmosphere, freer from cloud, and therefore refracting more light 

 than the rest. 



Taking Janssen's view, it may be accounted for by presuming 

 the planet to have travelled over a bright streak of corona, or 

 possibly an elongated prominence. 



It will be interesting to know whether coronal structiu-e was 

 seen by any of the observers. E. W. Pr INGLE 



Manantoddi, Wynaad, Jan. 15 



Ants and Bees 



In his recent paper on "Ants and Bees," Sir John Lubbock 

 is reported to have said — alluding to the bees which had tasted 

 the honey he had set for them : — 



"If bees had the means of communicating knowledge, no 

 doubt these bees would have told the others in the hive where 



