76 



NATURE 



\Nov. 25, 1880 



LETTERS TO THE EDITOR 



[The Editor dm not hold himself responsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, or 

 to correspond with the writers of, rejected _ manuscripts. No 

 ■notice is taken of anonymous commtinications.'] 

 The Editor urgently requests correspondents to keep their letters as 

 short as possible. The pressure on his space is so great that it 

 ts impossible othenvise to ensure the appearance even of com- 

 munications containing intereslins and no-jcl facts. 1 

 Fertilisation of Yucca 

 In Nature, vol. xxii. pp. 606, 607, appears a letter to which 

 my attention has only to-day been called— signed E. L. Layard 

 —on the subject of the fertilisation of yuccas successfully 

 introduced and cultivated in New Caledonia. 



The writer shows himself to be under some misapprehension 

 as to the generic characters and appearance of the insect which 

 is generally credited vith the fertilisation of these plants in 

 their native country. The moth of the genus Pronuba, to which 

 he refers, is not a "large moth having yellow under-wing^." 

 Although a common species belonging to the Noctuidiv, standing 

 in our British lists under the genus Triphana (Ochs), but included 

 ii\ Dr. Standinger's European Catalogue in the genus Agrotis 

 (Ochs), is distinguished by the specific, not generic, name fro- 

 nuha (Lin.), as well as by the characteristic appearance to which 

 your correspondent evidently alludes. 



The genus Pronuba (Riley) was founded for the reception of 

 Pronuba yuccasella (Riley) (see Proceedings Acad. Sci. Missouri, 

 ii pp. 55, 333; Report Nox. Ins. Missouri, v. 151, vi. 131; 

 Canadian Entomologist, iv. ^82 ; Hayden's Bulletin of the U.S. 

 Geological and Geographical Survey, iii. 121-141, &c.), which 

 has also been described by Prof. Zeller in the Verhandlungen 

 der zoologisch-botanischen Gescllschafl in Wien, 1873, vol. xxui. 

 pp. 232, 233, under the name Tcgeticula alba. 



This small white moth, of which some varieties have a few 

 black dots on the fore-wings, belongs to the Lepidopterous 

 sjroup Tineina (Stn.), possibly to the family Hyponomeuttd^. 

 i'rof. Riley finds that the female, which has the basal joints of 

 the maxillary palpi developed into a long curved tentacle fur- 

 nished with spines, uses these appendages to collect and convey 

 the joUen of the yucca to the tube of the stigma, which it could 

 not otherwise reach ; the eggs are then deposited, and the larva 

 feeds upon the fruit, subsequently hibernating and becoming a 

 pupa on the earth. It would be most interesting to ascertain 

 whether Pronuba yuccasella (Riley) has been introduced with 

 the yucca into New Caledonia, or whether any other insect, 

 cither indigenous or not indigenous to North America, has been 

 found to take its place in carrying on the work of fertilisation. 

 Prof. Riley considers the fact that yuccas introduced into the 

 more northern portions of America have failed to produce seed 

 may be attributed to the absence of Pionuba. 



If Mr. Layard will direct his attention to this point he can 

 scarcely fail to supply some valuable and instructive evidence 

 bearing upon the subject. Walsingham 



Eaton House, Eaton Square, November 13 



Skin Furrows of the Hand 



ALt-OW me to contribute the information in my possession in 

 furtherance of the interesting study undertaken by your Japan 

 correspondent (vol. xxii. p. 605). 



I have been taking sign-manuals by means of finger-marks tor 

 now more than twenty years, and have introduced them for 

 practical purposes in several ways in India with marked benefit. 



The object has been to make all attempts at personation or at 

 repudiation of signatures, quite hopeless wherever this method is 

 available. . ,. , u j- 



(I) First I used it for pensioners whose vitality has been a dis- 

 tracting problem to Government in all countries. When I found 

 all room for suspicion etfectually removed here, I tried it on a 

 larger scale in the several (2) registration offices under me, and 

 here I had the s.atisfaction of seeing every official and legal agent 

 connected with these offices confess that the use of these signa- 

 tures lifted off the ugly cloud of suspiciousness which always 

 hangs over such offices in India. It put a summary and absolute 

 stop to the very idea of either personation or repudiation from 

 the moment half a dozen men had made their marks and com- 

 pared them together. (3) I next introduced them into the jail 

 where they were not un-nceded. On commitment to jail each 



prisoner had to sign with his finger. Any official visitor to the 

 jail after that could instantly satisfy himself of the identity of the 

 man whom the jailor produced by requiring him to make a signa- 

 ture on the spot and comparing it with that which the books 

 showed. 



The ease with which the signature is taken and the hopeless- 

 ness of either personation or repudiation are so great that I 

 sincerely believe that the adoption of the practice in places and 

 professions where such kinds of fraud are rife is. a substantial 

 benefit to morality. 



I may add that by comparison of the signatures of persons 

 now living with their signatures made twenty years ago, I have 

 proved that tliat much time at least makes no such material 

 change as to affect the utility of the plan. 



For instance, if it were the practice on enlisting in the army to 

 take (say) three signatures— one to stay with the regiment, one 

 to go to the Horse Guards, and one to the police at Scotland 

 Yard — I believe a very appreciable diminution of desertions 

 could be brought about by the mere fact that identification was 

 become simply a matter of reference to the records. 



And supposing that there existed such a thing as a finger- 

 mark of Roger Tichborne, the whole Orton'imposture would have 

 been exposed to the full satisfaction of the jury in a single 

 sitting by requiring Orton to make his own mark for comparison. 



The difference between the general character of the ruga; of 

 Hindoos and of Europeans is as apparent as that between male 

 and female signaUires, but my inspection of several thousands 

 has not led me to think that it will ever be practically safe to say 

 of any sint^le person's signature that it is a woman's, or a 

 Hindoo's, or not a male European's. The conclusions of your 

 correspondent seem, however, to indicate greater possibilities of 

 certainty In single families I find myself the widest varieties. 



15 St. Giles, Oxford, November 13 W. J. Herschel 



p s —It would be particularly interesting to hear whether the 

 Chinese have really used finger-marks in this way.^ Finger-dips 

 (mere blots) are common in the East, as " marks." 



The Aurora of the 3r<i Instant 

 Mr. E. Dowlen has kindly communicated to me some parti- 

 culars of the above as seen by him at Southport. 



He first noticed the aurora at 6h. 50m. (it had however beeu 

 visible before that time) as a greenish white glow ;on the north 

 horizon. This gradually rose until 7h. 4Sm., when the top of 

 the arch was estimated at -two-thirds of the way up between the 

 horizon and the Great Bear. It then gradually died out from 

 the ends of the arch, and at 8h. 30m. had disappeared. During 

 the time it was watched the following changes took place :— 



From 7h. to 7h. iSm. it faded away from the eastern end until 

 7h ram., when nearly half the arch was gone. The western end 

 then seemed to gather itself up somewhat, and to get brighter. 

 After this the ends again lengthened out until 7h. 45™., when the 

 whole began to fade away. At 7h. 2Sm. a narrow-arched band 

 of black cloud concentric with the auroral arch was formed. It 

 seemed to start from the ends, and meet over the middle point. 

 At first this lay close upon the aurora. It then rose quickly, 

 passed through the Great Bear, and vanished. It took about 

 ten minutes to form, rise, and disappear. 



Mr Dowlen saw no streamers, but faint ones might have been 

 present and escaped notice owing to adjacent gas-lamps. 1 he 

 iurora was'at no time bright, and Mr. Dowlen doubts whether 

 any beyond the green line would have been seen m the 

 spectroscope ^^^^^^^.^^^ detailed seems to me of considerable 

 interest. J. Rand Capron 



Guildown, November 19 



Temperature of the Breath 

 There is no doubt that Dr. Roberts has discovered the true 

 explanation of the phenomena that puzzled me and a good 

 miny others to whom I showed them. I have repeated Di. 

 Roberts's method of heating the enveloping material so as to 

 expel all moisture from it, cooling it down to the temperature of 

 the room and then breathing through it. In every case where 1 

 did so the thermometer showed a rise to 112 and upwards at tbe 

 end of a minute; at the end of two minutes the index was 

 pushed into the small bulb at the top, shoxying a temperature of 

 about 116° It is evident, therefore, that the high temperature 

 observed is not the actual temperature of the breath, but «s 



