August 4, 1904] 



NA TURE 



ii9 



them is improper. A nomenclatural technicality should not 

 be allowed to obscure the facts. 



(2) " .\ subspecies elevated to specific rank retains the 

 same name, unless the resulting binomial has been 

 previously published." Hovifever, Juncus acuminatiis 

 robuslus, Engelm., iS6S, though a valid species, does not 

 become Juncus robuslus, because of Juncus yobustus, 

 S. Wats., 1879. Further on, we read, " A specific or sub- 

 specific name is a homonym when it has been published 

 for another species under the same generic name. Two 

 subspecies of the same genus shall not retain the same 

 name." If two subspecies in a genus may not retain the 

 same subspecific name, as I suppose is intended, though not 

 clearly stated,' may a species and a- subspecies do so? It 

 appears logically to follow, though again it is not stated, 

 that they may not. Hence in the above case of Juncus, the 

 Watsonian Juncus robuslus is invalid from the first, because 

 of the Engelmannian subspecies, and there would result 

 from the combination of these rules the dropping of the 

 name " robuslus " altogether, which seems absurd. 



(3) " .A generic or subgeneric name is a homonym when 

 previously published, or proposed in print, for another 

 genus." But we are not told whether the publication of 

 a subgeneric name precludes its use in another sense for a 

 genus, or whether when a subgenus is elevated to generic 

 rank it is obligatory to use the subgeneric name, if it is 

 not a homonym. These things are recognised by zoologists, 

 and it does not seem proper for the botanists to ignore them 

 in their code, and then do as they individually please. 



(4) Names are considered identical when " mere variations 

 in the spelling of the same word." This seems to me a 

 dangerous rule, and illogical since it ignores the fact that 

 names belong to the objects they designate, independent of 

 derivation. By considering derivation, one can prove that 

 crab and crayfish are " mere variations " of one word," and 

 most assuredly Theodore and Dorothy are one ! The e.x- 

 amples cited in the code e.xpressly exclude differences of 

 gender in generic names as valid distinctions, and while the 

 specific names Greenei and Greenii (after Greene and Green) 

 are admitted, we are not allowed virginianus and 

 virginiensis. In this last case, I think a difference in the 

 sense of the adjective may be detected, apart from its appli- 

 cation to the plant. It is the same difference that is found 

 between the statements that a man is English, and that he 

 lives in England. One refers to quality, the other to place. 



(5) Hybrids may be named like species, with the sign x 

 before, as X Sali.x capreola. I should prefer to write 

 Salix X capreola. The naming of hybrids in this manner 

 seems necessary, on account of the possible instability of 

 the combination-names. Thus Caslilleia confusa x 

 acuminata, Ckll., Bat. Gazette, April, igoo, p. 280, is better 

 called Caslilleia x Porterae (a name I have long had in 

 MS.), because the plant formerly known as acuminata is 

 now called by a different name. T. D. A. Cockerell. 



Colorado Springs, Colorado, May 21. 



The Formation of Coral Reefs. 



Seeing (N'.4tl-re, .'\pril 21, p. 581) that this delicious bone 

 of contention has once more been clawed from its resting 

 place, I would beg editorial permission to join in discuss- 

 ing it. 



That dead coral is soluble in warm seas is indisputable, 

 but that solution in coral regions exceeds deposition is an 

 issue to be tried not in a European laboratory, but on a 

 coral reef. It is claimed that the lagoon of an atoll was 

 excavated by solution, and that the matter removed was 

 poured into the open sea through the reef channels. In 

 opposition to this I reply that the central floor of a lagoon 

 in process of excavation should present a bare surface of 

 eroded rock like the basin excavated by a waterfall ; but 

 the middle of a lagoon floor has been shown by many 

 observers, and especially by Mr. G. H. Halligan's boring, 

 to consist of weed, mud, sand, and shingle. These are 

 indications of an area of accumulation, not erosion. Let 

 those who believe that the lagoon floor is dissolved away 

 produce water from the seat of action heavily charged with 

 solution ! 



Again, it is contended that the water flowing from the 



1 It is, however, clearly indicated by an example given 

 - Krebis, Itrebs, crab : krebis, ecrevisse, crayfish, and A 



NO. 1814, VOL. 70] 



lagoon through the exit channels bears away in suspension 

 and solution both matter excavated from the lagoon floor 

 and matter washed by the waves into the lagoon. In deny- 

 ing that either is so drained away to any considerable extent, 

 I would point out that water unarmed with sediment has no 

 cutting power ; but if the exit channels conveyed heavily 

 charged water, the sand blast thus produced would cut tO' 

 pieces every living thing in the passage. By my observ- 

 ations these passages are well carpeted with luxuriant life. 

 To elucidate this important point the next biologist to re- 

 port on coral fauna might be instructed to survey a main 

 lagoon passage in detail. 



If, as I maintain, the lagoon is an area of rapid accumu- 

 lation from both growth and deposition, then, if no sub- 

 sidence of the atoll occurs, the lagoon must in time be 

 filled in. Every phase from 9 chain of islets to an atoll 

 filled in solid is represented in the Pacific. 



The destiny of every lake and pool on the earth's surface 

 is to be obliterated by alluvium. It is here contended that 

 the inevitable fate of a stationary atoll is the same, the 

 only difference being that matter is poured from above into 

 the terrestrial lake, whereas it is washed up from below 

 into the atoll lagoon ; but, as Darwin observed, while sub- 

 sidence continues it will preserve to the atoll its lagoon. 



Charles Hedley. 



Australian Museum, Sydney, N.S.W., June 20. 



The Traction of Carriages. 



In reference to a letter on the above subject in your issue 

 of July 21, the draught of a vehicle depends largely, though 

 not entirely, upon the ratio that exists between the distance 

 from wheel to wheel and the height of the centre of gravity 

 from the ground. If the wheels are far apart and the 

 centre of gravity low, the carriage is hard to draw ; if the- 

 wheels are closer or the load higher, the draught is lighter^ 



The reason for this fact may, I think, be readily seen by 

 the following illustration ; — Let us suppose a bicycle and 

 rider, the centre of gravity four feet above the road, and 

 vertically mid-way between the wheels. For the present 

 purpose we will disregard the effect of springs and of speed. 

 If the front wheel goes over a stone, say, two inches high,, 

 the centre of gravity, or load, is partly lifted vertically and 

 partly thrown back over the hind wheel, describing, with 

 relation to the machine, part of a circle having its centre 

 at the point where the hind wheel touches the ground ; and 

 if the wheels are four feet apart, centre to centre, the load 

 is raised about half an inch and moved backward to a 

 much greater extent. 



But we can imagine a bicycle of the same weight and 

 having the same load with wheels, say, forty feet apart, 

 and if this machine meets the same obstacle the load will 

 be lifted nearly a full inch, the back-throw being scarcely 

 perceptible ; or, on the other hand, we may conceive of a 

 bicycle with wheels four feet apart and the centre of gravity 

 forty feet high, in which case the two-inch stone will scarcely 

 lift the load at all, but only send it (dangerously, no doubt) 

 back over the hind wheel. 



Heavy draught depends upon, or is caused by, having to 

 lift the centre of gravity rapidly, and may be lightened by 

 easy springs, large wheels, putting the load high, or putting 

 the wheels near together. Cecil G. Savnders. 



Tower House, Canonbie Road, Forest Hill, S.E., July 25. 



The Word Cingalese. 



On p. 131 of the current volume of Nature, the expression 

 " Cingalese fishes," and on p. 78 of the same volume the 

 expression " Cingalese outlier " are found. The word 

 Cingalese is also used in the " Cambridge Natural History " 

 (Mollusca) to denote a subregion. In the first place the 

 word should be spelt Sinhalese, the form above quoted being 

 a quite incorrect transliteration. In the second place, the 

 adjective corresponding to Ceylon is Ceylonese, the word 

 Sinhalese meaning " of or belonging to the Sinhalese race." 



Ceylon, July 6. A. K. Coomaraswamy. 



Residual Affinity. 

 If Mr. Pickering has imagined that fractions of a charge 

 are necessary, and has not discriminated between fractions 

 of a charge and fractions of a bond, it is not surprising that 

 his contribution of thirteen years ago failed in impressive- 

 ness. Oliver Lodge. 



