July lo, 1879] 



NATURE 



243 



fall will be very rapid, both on account of gravitation and attrac- 

 tion, and (a) the evaporation will be so great, that it will he frozen. 

 On touching the cloud B it condenses (b) part of its vapour, gets 

 thus a coating of ice, and, having the same fluid as B, it will be 

 repelled towards A, and 50 on, downwards and upwards, until it 

 becomes heavy enough to fall to the ground." 



My difficulties are the following : — Whence comes the evapo- 

 ration spoken of at (a) ? 



According to the above, when it reaches B it is frozen. What 

 then am I to understand by the "condensation of part of its 

 vapour (b) ? " 



Also, would not the two clouds, A and B, having oppoite 

 fluids, themselves unite ? 



If you will kindly solve me these difficulties you will greatly 

 obliije an Ignoramus 



Butterfly Swarms 



With reference to the case mentioned in Nature, vol. xx. 

 p. 220, I agree with your correspondent that " local fecundity " 

 cannot be the cause of the great number of Vanessa carditi 

 observed this year in the south of England, more especially as 

 this species does not emerge from the chrysalis until the end of 

 July at the earliest. It therefore appears to me probable that 

 the specimens observed have migrated (having hybernated) from 

 the Northern Counties or even from Scotland, in consequence of 

 the exceptional severity of the weather this season. I would 

 also suggest that the "periodical abundance" of this butterfly, 

 as " also that of Colias hyale and Edusa, besides several others, 

 may be caused by some peculiarity in the food-plant itself. This 

 is rendered more likely by the fact that both Colias hyale and 

 Edusa, which feed upon plants of the Leguminous order, and 

 often of the same species, appear in great abundance at the same 

 period. 



I may mention that where I reside I observed many specimens 

 of Vanessa cardiii\a%t year (1878). In the preceding year (1877) 

 both Colias hyale and Edusa were exceedingly plentiful, whereas 

 last year (1878) I did not see a single specimen of either of these 

 butterflies. F. H. Haines 



The Buses, Edenbridge, Kent, July 7 



Mr. J. H. A. Jenner says (Nature, vol. xx. p. 220) that 

 " last season (1878) he saw no specimens of Vanessa cardui, nor 

 did he hear of any about Lewes." I would remark that Vanessa 

 cardui was exceedingly abundant in the Isle of Wight ; I could 

 have caught scores in a few minutes. I would further remark 

 that towards the close of the season I saw beds of nettles, many 

 yards square, literally black with larvae of V. cardui.^ I antici- 

 pated then that they would be abundant this year, and so they 

 are. W. Rees Swain 



Patent Museum, South Kensington, July 4 



Intellect in Brutes 



As an instance of intelligence in a cat, the following story is, 

 I think, worthy of being recorded in your pages : — 



My father, when a boy, kept a tame starling, which, having 

 had its wings chpped, was allowed to hop about the house at 

 random. It had been brought up, so to speak, with a little 

 kitten, and a great friendship had been established between 

 the two, they i laying together, drinking out of the same saucer, 

 &c. , &c. 



One day while the family were at dinner, with open doors, 

 the cat suddenly pounced upon the starling, and every one 

 thought that at last the cat's nature had got the better of its 

 affection ; but no. The cat carefully took up the starling, 

 jumped V. ith it on to a table, and leaving it there, rushed out of 

 the room. 



A moment after, the sound of a furious fight going on in the 

 liall reached the ears of the astonished family, and it was then 

 found that a strange cat had stolen into the house, with which 

 the starling's friend was fighting. Evidently the house cat heard 

 the approach of the enemy, and having first placed its play- 

 fellow in a comparatively safe place, rushed out to expel the 

 intruder. A. Dupre 



Kensington, W., July 5 



' [The Lirva: referred to were probably those of K atalauta. V. cardui 

 ordiiuuily feeds on t/iitlles.—^D.] 



The letters of X. and of Mr. Henry Clark in Nature, vol. 

 XX. p. 220, referring to the recognition of portraits by dogs, are, 

 I think, very interesting, as my observations lead me to suppose 

 that it is very rarely that a dog takes any notice of a painting or 

 any representation on the flat. I only know of one instance. 

 A bull terrier of mine was lying asleep upon a chair in the house 

 of a friend, and was suddenly aroused by some noise. On 

 opening his eyes, the dog caught sight of a portrait of a gentle- 

 man on the wall not far from him, upon which the light was 

 shining strongly. He growled, and for some little time kept his 

 eyes fixed upon the portrait, but shortly satisfying himself that 

 there was no danger to be apprehended, he restuned his nap. I 

 have often since endeavoured to induce him to pay some atten- 

 tion to portraits and pictures, but without success ; but some- 

 times he will bark at his own reflection in a looking-glass. He 

 knows it to be his own image that he sees, for he very soon tires 

 both of barking and looking. Other authentic instances of this 

 kind would be valuable. J. B. R. 



July 4 



I SEND the inclosed extract from the Bedworth Guardian. I 

 can vouch for the fact, as Hawkesbury Station is near to me,'and 

 my son has witne; sed the feats of poor Pincher. I trust that 

 it will not be an imwelcome contribution to the interesting series 

 of facts in evidence of animal sagacity recorded in Nature. 



Moat House, Walsgrave, Coventry, July 3 



J. S. Whittem 



" The picturesque little station at Hawkesbury Lane, between 

 Nuneaton and Coventry, has, for some time past, been the home 

 of a fox terrier, known as Pincher, an animal possessing almost 

 human intelligence. Pincher — trained by its owner, Mr. 

 Instone, to do so — would listen with marvellous patience and 

 acuteness for the signal intimating that a train was approaching 

 the station, and then, almost with the speed of lightning, rush 

 to the signal-box, and, seizing the bell between its teeth, shake 

 it heartily, and thus apprise the waiting passengers of the train's 

 approach. This task accomplished, he would descend the steps 

 leading from the box, proudly wagging his tail, and ready and 

 willing, apparently, for any duty he might be called upon to 

 perform. Often, as a train was leaving the station, Pincher 

 would run beside it for about a hundred yards, as though acting 

 under the impression that the engine-driver would be unable to 

 obtain the necessary impetus without his assistance. On Sun- 

 day evening last Pincher's career was brought to an untimely 

 end, but he died as became a dog of his attainments and renown, 

 " in harness." Soon after seven o'clock on the evening named, 

 two trains entered the station at one and the same time (Pincher 

 having previously rung the bell), one going towards Nuneaton, 

 the other in the contrary direction. Actuated by some motive 

 or other — probably to see what was going on at the other side 

 of the line — the dog darted under the carriages of the latter 

 train, and one of the wheels passed over his neck, death being 

 instantaneous." 



Snails z'. Glow-worms 



When writing on this subject I thought my facts might be 

 questioned, but I did not expect they would be so distorted as 

 they have been by Mr. McLachlan at p. 219. 



I simply recorded what I had seen, and in accordance with the 

 request at the kead of your column for letters to the Editor, I 

 made my letter "as short as possible." 



The heading of my letter was correct, and I described what I 

 certainly saw — a glow-worm in the inside of a snail, for when the 

 snail moved its semi-transparent skin was between me and the 

 light. There was no phosphorescent matter on the snail. 



If the glow-worm was eating the snail,'as both Mr. McLachlan 

 and Mr. Greenwood Penny suggest, then, I conclude, he attacked 

 the liver, and not the lights, as Mr. Henslow's cat did ! At all 

 events my opponents will agree with me in thinking that the 

 snail had a light supper ! The fact is evidently new to these 

 gentlemen. 



I shall feel obliged by any or all of them sending me some 

 glow-worms, and I will try the experiment again, as h ell as some 

 others. R. S. Newall 



Gatesheadon-Tyne, July 8 



Occurrence of Boar Fish 



I RECEIVED several notices of the capture of boar-fish {Capros 

 aper), on the south and ;outheast coasts of England during June 



