igo 



NA rURE 



[December 17, 1908 



connected wiih the periodic variation, will presently appear 

 in the Scottish Reports of the North Sea Investigation 

 Committee. D'Arcy W. Thompson. 



University College, Dundee, December g. 



Reform of Zoological Nomenclature. 



The labours of the committee proposed by Mr. Boulenger 

 at the British Association for remedying the abuses of 

 zoological nomenclature will be enormous, even if restricted 

 to the settlement of common generic names. To hope that 

 they should extend to large numbers of species, or to 

 species of the less prominent groups, is, I fear, impossible 

 unless a more wholesale method cf dealing with the names 

 be adopted. 



The necessity for extending the settlement to a largo 

 number of species of such groups as the Polychait,a i.s very 

 pressing, since hundreds of names were given by the earlier 

 workers, whose limited knowledge of the group made 

 their giving a moderately adequate description of the 

 species named an impossibility or apparent superfluity. 

 Without some such arrangement as that proposed below 

 the nomenclature of this and other similarly placed groups 

 will remain in a state of flux for years beyond our genera- 

 tion, and in consequence the labours of the conscientious 

 worker will be not so much to the advancement of know- 

 ledge as to the weighing of all sorts of circumstantial 

 and fragments of documentary evidence to determine what 

 some culpably incomplete description really refers to. As 

 a case in point see the list of synonyms for Aphroiite 

 aculeata in Mcintosh's " Monograph of the British 

 .Annelids," and consider the patient and learned labour 

 spent on that compilation which might have been employed 

 in direct scientific investigation. Then compare a case 

 where the species dealt with is not a rather isolated and 

 very well-marked form, but one having several related 

 species living in its vicinity, none of which have any very 

 strilving characteristic ! The labour in such a caso is end- 

 less, the conclusion arrived at being always liable to be 

 upset by some purely circumstantial evidence accidentally 

 coming to light. 



So far as I can see, the only way in which species 

 names can be dealt with' wholesale, and several thousand 

 names be given priority, once and for all, is for the com- 

 mittee to confine themselves to the consideration of books 

 rather than to individual names. I should suggest that 

 experts in the systematic literature of each group prepare 

 short lists of the most important descriptive works. Care 

 wfiuld be taken to include only such works as contain a 

 good number of definitions of genera and descriptions of 

 species, and that the descriptions should be adequate and 

 well illustrated. The number of works in each group 

 would not be large, but the number of species contained 

 would be much greater than could possibly be dealt with 

 by any committee attempting to determine the extent of 

 usage of each name separately. The names given to 

 species described, w^hether as new or not in this selec- 

 tion of works, would be made unalterable. In case of 

 synonymy within the list, the rule of priority would apply. 



To give an example, again, from the Polychaeta. ' I 

 should suggest the following works to be among those the 

 nomenclature of which should be inviolable : — 



(i) ClaparMc, " Annelides Polych^tes du Golfe de 

 Xaplos " (but possibly not his other work on PolychfEta 

 from near the Spanish frontier). 



(2) Ehlers, " Die Borstenwurmer," and several recent 

 works on South .American collections. 



(j,) Mcintosh, " Challenger Reports," vol. xii. The 

 Chiillenger reports would all be reckoned authoritative, I 

 suppose, thus securing an immense number of settled 

 names at once. 



(4) Mcintosh, " Monograph of the British Annelids." 



Some famous works, e.g. Kinberg's and Grabe's, even 

 the lattor's " Annulata .Semperiana " I oersonallv should 

 not include, and some voluminous recent literature certainly 

 should be omitted. I do not mean that such works should 

 be allowed to lose any of the usefulness thev have at pre- 

 sent, but should be searched rather for their facts than 

 their namings. 



My plan wmII certainly cause some unjust neglect of 

 some few well-made descriptions of species, but can anv 



beneficent and effective legislation, on any subject what- 

 ever, be framed- to avoid all injustice to small minorities? 

 In comparison with the injustice which gives any easy- 

 going name-giver authority to mar the work of the 

 laborious describer, this is nothing. 



It has the advantage of substituting the authority of 

 series of the best works for that of the committee. 

 Cavillers may object to the most authoritative committee 

 of living and possibly interested men, but are less able 

 to object to this reinforcement of the authority of the 

 most eminent w^orkers in each group, many of whom are 

 now beyond all personal interest in the preservation or 

 neglect of their particular systems of nomenclature. 



My plan is doubtless full of difliculties, but I believe 

 not more so than any other proposed, while the remedy 

 I goes deeper, not, as in other cases, merelv touching the 

 surface of this great hindrance to progress and order. 



Cyril Crossland. 



Port Sudan, Red Sea, November 13. 



Mercury Bubbles and the Formation of Oxide Films 

 by Water containing Oxygen in Solution. 



The formation of mercury air bubbles described by Mr. 

 Wright, Sir William Crookes, Mr. Hare, and Prof. Dixon 

 seems to be a different phenomenon from that described 

 by the late Prof. P. G. Tait in his " Properties of Matter " 

 (1899, p. 257) in the following passage ; — 



"■ Even so dense a liquid as mercury can be formed into 

 a bubble. We have merely to shake a glass bottle filled 

 with water and clean mercury. The bubbles which form 

 on the mercury (often detached) are full of water. Some- 

 times we sec others coming up from the interior of the 

 mercury. These are water-skins full of mercury." 



I have repeated Tait's experiment, using a 250 c.c. 

 bottle containing about 50 c.c. of mercury and tilled quite 

 full of water. A short, vigorous shaking fills the bottle 

 with a foam of mercury bubbles, which quickly subsides, 

 leaving some isolated bubbles, which also quickly sink 

 to the bottom and disappear in the mass of mercury. The 

 bubbles formed in this way are therefore mcixury water 

 bubbles, not mercury ah bubbles. The addition of 

 sulphuric acid to the water .stops the formation of bubbles ; 

 the shaking then breaks up the mercury into minute solid 

 globules. 



During the experiment an observation was made which, 

 while it does not bear directly on the formation of mercury 

 bubbles, is perhaps of some interest. It was found, when 

 water which had not been freed from dissolved gases was 

 used, that the liquid set free by the bursting of the bubbles 

 had a smoke-brown colour by transmitted light. As the 

 foam subsides into the mercury below, this brown cloud 

 is left floating over the surface of the mercury. The 

 cloud left by the bursting of single bubbles can sometimes 

 be observed floating in the upper part of the liquid. With 

 water that has been freed from dissolved gases by boiling 

 this appearance does not occur. 



The browned water, after standing for a few minutes, 

 was decanted into a clean vessel, and was watched for 

 about an hour. During this time no deposit settled from 

 the liquid. A drop of the liquid was then examined under 

 the microscope with illumination by an intense oblique 

 beam of reflected light, and also by transmitted light with 

 a high-power objective. Two kinds of particles w-ere pre- 

 sent, minute globules of mercury measuring from 2000 

 lo 6000 iifji, and shreds and spicules of oxide film. The 

 latter, which are only visible under the oblique beam, are 

 in constant pedetic movement. They arc not spherical 

 aggregates, but minute plates, which appear and disappear 

 as they turn and twist in the unidirectional beam of light. 

 The oxide film which forms on the stretched mercury 

 surfaces has, no doubt, the same microstructure as I have 

 found alike in solid and in liquid films — a kind of lenticular 

 granulation due to surface tension. The sudden collapse 

 of the mercury film sheds the oxide film, and causes it to 

 break up into minute lens-like plates or spicules, which 

 are in pedetic movement. In some cases these plates form 

 aggregates of considerable size round the ininute mercury 

 flobules. These aggreg-atos are sufficientlv massive to be 

 visible by transmitted light. G. T. Beii.by. 



Glasgow, December 12. 



NO. 2042, VOL. 79] 



