NATURE 



\Nov. 6, 1873 



and waited until the deer was water-logged. Their prey being 

 thus rendered heavy and short-winded, would fall an easy victim 

 if induced to run sufliciently far, — i.e. if prevented from entering 

 the jungle. It %\as, of course, impossible to estimate the number 

 of jackals engaged in this hunt, for it is not unlikely that, as soon 

 as one had done duty at one place, it outran the deer to await it 

 in the another. 



A native servant, who accompanied my friend, told him that 

 this was a stratagem habitually employed by the jackals in that 

 place, (and that they hunted in sufficient numbers "to leave 

 nothing but the bones." As it is a stratagem which could only 

 be effectual under the peculiar local conditions described, it must 

 appear that this example of collective instinct is due to "separate 

 expression," and not to " inherited habit." 



Cases of collective instinct are not of infrequent occurrence 

 among dogs. For the accuracy of the two following I can vouch. A 

 small skye and a large mongrel were in the habit of hunting 

 hares and rabbits upon their own account, the small dog having 

 a good nose and the large one great fleetness. These qualities 

 they combined in the most advantageous manner, the terrier 

 driving the game from the cover towards his fleet-footed com- 

 panion, which was waiting for it outside. 



The second case is remarkable for a display of sly sagacity. 

 A friend of mine in this neighbourhood had a small terrier and a 

 large Newfoundland. One day a shepherd called upon him to 

 say that his dogs had been seen worrying sheep the night before. 

 The gentleman said there must be some mistake, as the New- 

 foundland had not been unchained. A few days afterwards the 

 shepherd again called with the same complaint, vehemently as- 

 serting that he was positive as to the identity of the dogs. Con- 

 sequently, the owner set one watch upon the kennel, and another 

 outside the sheep-enclosure, directing them (in consequence 

 of what the shepherd had told him) not to interfere with 

 the action of the dogs. After this had been done for several 

 nights in succession, the small dog was observed to come at day- 

 dawn to the place where the large one was chained : the latter 

 immediately slipped his collar, and the two animals made straight 

 for the sheep. Upon arriving at the enclosure the Newfound- 

 land concealed himself behind a hedge, while the terrier drove 

 the sheep towards his ambush, and the fate of one of them was 

 quickly sealed. When their breakfast was finished the dogs re- 

 turned home, and the lirge one, thrusting his head into his collar, 

 lay down again as though nothing had happened. Why this 

 animal should have chosen to hunt by stratagem prey which it 

 could easily have tun down, I cannot suggest ; but there can be 

 little doubt that so wise a dog must have had some good 

 reason. 



Dunskaitb, Ross-shire, Aug. 18 GkorgeJ. Romanes 



In your number of August 14 (Vol. viii. p. 302) Mr. 

 E. C. Buck alluded to the curious and interesting instances 

 of instinct and gregarious action in lower animals, and men- 

 tioned that this action has been more particularly observed 

 in the case of wolves in India. These remarks remind 

 me of a curious instance of combined action between two foxes 

 for the capture of their prey, which I witnessed myself more 

 than once ; and as similar proceedings, on the part of these ani- 

 mals have been so frequently observed in the hilly country of 

 the department in which I reside, I cannot but conclude that the 

 same habit will prevail among them, wherever they are found. 

 The case is as follows : — One of the two foxes, in the pursuit of 

 a rabbit or hare, continued yelping at short and regular intervals 

 and thus drove the unsuspecting victim in the direction of the 

 appointed bush, \ihere the other fox was concealed and ready to 

 seize its prey as soon as it came within its reach. The capture 

 being effected, they generally divide the prey between them ; but 

 if the ambushed fox, in jumping at its prey, has not gained the 

 end in view, the two baffled compeers alternately repeat many 

 times the unsuccessful leap, in order probably to find out the 

 cause of the miscarriage. 



The above allusion to foxes leads me to mention another in- 

 stance of the ingenuity of these animals, which is very remark- 

 able, and one, I believe, which is but little known. On one 

 occasion, in early life, when I happened to pass my College 

 vacation at the Chapelle d'Angillon (Department of the Cher), 

 my attention was attracted twice or three times, when rambling 

 by the side of a small stream called the Petite-Saudre, by a float- 

 ing mass of moss, which, when drawn to the bank, was found 

 to be swarming with fleas. An old peasant of the neighbour- 

 hood, who observed my surprise, gave me the following explana- 

 tion of the fact, the correctness of which, said he, he could 



warrant : — Foxes are much toimented with fleas, and when the 

 infliction becomes severe, they gather, from the bark of trees, 

 moss which they carry in their mouths to the side of a stream 

 where the water deepens by degrees. Here, they enter the 

 water, still carrying the moss in their mouths ; and, going back- 

 wards beginning from the end of their tail, they advance by slow 

 degrees, till the whole body of the animal, with the exception of 

 the mouth, is entirely immersed. The fleas, during this pro- 

 ceeding, have rushed successively in rapid haste to the dry parts 

 and finally to the moss, and the fox, when he has, according to 

 his calculation, allowed sufficient time for all tlic fleas to take 

 their departure, quietly opens his mouth. The floating moss, 

 with its interesting freight, is carried away by the stream, and 

 the animal finds its way back to the bank, with an evident feel- 

 ing of much self-satisfaction at having thus freed himself from 

 his tormentors. 



Many persons, and very trustworthy ones, confirmed to me 

 the old peasant's account. 



Montpellier, Oct. 17 A. Paladilhe 



Venomous Caterpillars 



Once before I wrote to you on this subject, and had hoped 

 that the entomological mountain had long since been safely deli- 

 vered of its mouse. But from recent communications such ap- 

 pears not to be the case. 



Any large caterpillar with tolerably stiff hairs that will not, in 

 different degrees, affect tender skin when brought incautiously 

 in contact, may probably be looked upon as a phenomenon. 

 That any larva with stiff spines will occasion inconvenience by 

 more violent contact is, I should think, evident to any thinking 

 naturalist. That inflammatory symptoms will most probably 

 follow in either case is also evident. The puncture made by a 

 single steel filament would occasion little or no inconvenience ; 

 liut if multitudes of these filaments were simultaneously directed 

 on a limited surface of skin, the result would be very different. 

 The best analogue of the irritation caused by larval hairs is, as I 

 before hinted, to be found in that following the handling of cer- 

 tain boraginaceous plants — Echium vulgarc, Symphytum offici- 

 nah; &c. 



Mr. Riley, the State Entomologist for Missouri, has, in his 

 fifih annual report, devoted a chapter to this subject, and states 

 that he is acquainted with fifteen indigenous larva; having so- 

 called urticating powers, and in every instance the action is 

 mechanical. Those observers who place so much stress upon the 

 fact of contact with a hairy larva causing pain should not let sur- 

 prise get the better of their judgment ; nor, in the case of those 

 residing abroad, should they allow themselves to be influenced 

 by native superstitions. The position is simply this : any hairy 

 larva is likely to cause irritation mechanically, from particles of 

 the numerous hairs piercing the skin ; no case has yet been 

 proved in which such irritation is the result of venom, such as 

 that of Crtica among plants. 



Lewisham, Oct. 10 R. McLachlan 



Harmonic Echoes 

 The phenomenon mentioned by W. G. M. of notes higher in 

 pitch than the sound producing them being reflected from rail- 

 ings, is not at all uncommon, and is very easy of explana- 

 tion. Suppose a person standing close to a line of upright 

 bars, the distance between the bars being . o . If he now 

 makes any sharp sound, so as to propagate a single wave, 

 this wave will be successively reflected by each of the bars ; so 

 that, in answer to the single wave 'he propagates, he will have 



(V being the velocity of sound). If, however, he stands at any 

 distance, say k, from the row of bars, he ought to get a slightly 

 descending ec''0, as then each wave succeeds th e Ust at a dis- 

 tan:e increased by twi:e the difference between sjn- •)■ «'<?- and 

 \Ik^ -t- (« — l)-a°, where « is the number of the bar measured 

 from opposite the observer. Arnulph Mallock 



Erampford Speke, Oct. 13 



Evolution as applied to the Chemical Elements 



When so little is really known about evolution, even in the 

 sphere of organic matter, where this grand principle wa» first 



