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NATURE 



[June 8, 1882 



The chloroformed ants were treated by their companions 

 as dead, but the intoxicated ones were recognised and 

 taken into the hive, while intoxicated strangers were 

 rejected. The manner in which recognition is effected 

 has long been a standing puzzle to observers, and although 

 Sir John Lubbock has not shown " how it is done," he 

 has at least shown very conclusively how it is not done. 

 Previous hypotheses supposed the faculty to depend on 

 recognising personal appearance, personal scent, or on 

 there being some pass-signal understood by all the mem- 

 bers of a hive, and not known to members of other hives. 

 But Sir John has found that the recognition is effected 

 when the pupae are hatched out away from their native 

 hive, and even when the eggs are developed in one half of 

 a divided hive, and the matured insects then returned to 

 the other half. He also found that the memory of com- 

 panions or nest-mates extends over at least a year and 

 nine months. 



Regarding the power of communication, the experi- 

 ments went to show a strange uncertainty, though they 

 agree with previous observations in establishing the main 

 fact that such a power exists. Thus, for instance, when 

 a dead fly was pinned down so that the ant which found 

 it could not drag it towards the nest, she returned to the 

 nest and procured assistance. This experiment was 

 repeated, with small variation, a great number of times, 

 and certainly proves a power of communication at least 

 to the extent of " follow me." Moreover, by an ingenious 

 device with three parallel tape bridges extending from a 

 nest to three similar glasses, one empty, another holding 

 a few larvae, and the third filled with many larvae, Sir 

 John was able to show- the interesting fact that ants 

 can give definite information to one another as to 

 locality, without requiring merely to lead the way. For 

 he took two ants and placed one of them to the glass with 

 many larvae, and the other to that with a few. Each of 

 them took a larva, carried it to the nest along the respec- 

 tive tapes, returned for another, and so on. After each 

 journey he put another larva in the glass with a few larvae 

 to replace the one which was taken away. Every new 

 ant which came to either of the glasses was imprisoned 

 till the end of the experiment. Such being the condi- 

 tions, it was observed that no ants went along the tape 

 bridge to the empty glass, 104 ants went to the glass with 

 a few larvae, and 304 to the glass with the many larvae. 

 Thus it seems that the two original (marked) ants were 

 able to tell their companions, not only where larva; were 

 to be found, but even where the largest store was to be 

 met with. 



Concerning the powers of special sense, a large number 

 of experiments proved that ants are able to appreciate 

 colour, and when their nests are covered with slips of 

 stained glass, analysis of some of these experiments 

 showed that there had congregated " under the red 890, 

 under the green 544, under the yellow 495, and under the 

 violet only 5." Other experiments showed that red light 

 was the same to them as darkness, or, at least, that about 

 the same proportion of ants congregated under red glass 

 as congregated under a slip of porcelain. With reference 

 to the parts of the spectrum invisible to our eyes, other 

 experiments proved "that the limits of vision of ants at 

 the red end of the spectrum are approximately the same 

 as ours, that they are not sensitive to the ultra-red rays ; 



but, on the other hand, that they are very sensitive to the 

 ultra-violet rays." A layer of sulphate of quinine or of 

 bisulphide of carbon had the effect, as might be supposed 

 from the latter statement, of rendering the ultra-violet 

 rays invisible, or less obnoxious to the ants. Conversely, 

 a saturated solution of chrome alum, and chromium 

 chloride in a layer so thick that in the darkness beneath 

 it the ants could not be seen, had the effect of inducing 

 the ants to escape from its luminosity to their eyes, and 

 to go beneath the bisulphide of carbon ; so that, " though 

 to our eyes the bisulphide of carbon is absolutely trans- 

 parent, while the chrome alum and chromium chloride 

 are very dark, to the ants, on the contrary, the former 

 appears to intercept more light than a layer of the latter." 



A number of elaborate experiments on the sense of 

 hearing produced only negative results, though from other 

 considerations (chiefly anatomical) Sir John concludes, 

 " On the whole, though the subject is still involved in 

 doubt, 1 am disposed to think that ants perceive sounds 

 which we cannot hear." Experiments on the sense of 

 smell showed that the estimate previously formed by 

 naturalists of its excellence was not exaggerated. 



A number of experiments on the general intelligence of 

 ants in overcoming difficulties of various kinds which Sir 

 John devised for them, went to indicate a poverty of 

 resources scarcely to have been expected ; but it must be 

 remembered that this only shows that there are ants and 

 ants, for other trustworthy observers give wonderful 

 accounts of the high intelligence of certain foreign spe- 

 cies. On the subject of way-finding, there are also many 

 interesting observations, which show that sight is not of 

 nearly so much service as smell, although it is of much 

 use in giving them their general " sense of direction ; " 

 for they observe the direction in which light is shining, 

 guide themselves accordingly, and lose themselves if 

 turned partly round on a rotating table in the dark. 



We must not leave these chapters on ants without re- 

 ferring to one on the relation of these insects to plants, 

 and another on their relation to animals. It is of im- 

 portance to many species of plants that they should not 

 be visited by ants, as the presence of these insects would 

 tend to keep away bees, &c, which are required to fer- 

 tilise the flowers. Consequently, these species of plants 

 present a great variety of contrivances to exclude the 

 ants, such as water-traps, slippery surfaces, narrow pas- 

 sages, sharply-curved stalks, hairs, viscid secretions, &c. 

 Instances of such contrivances are given, and the general 

 conclusion is stated that "though ants have not influenced 

 the present condition of the vegetable kingdom to the same 

 extent as bees, they have also had a very considerable 

 effect upon it in various ways." Concerning the relation 

 of ants to other animals, the most interesting addition to 

 our knowledge which Sir John has made is that of 

 Lasiusflavus farming the eggs of aphides. For " here 

 are aphides, not living in the ants' nests, but outside, on 

 the leaf-stalks of plants. The eggs are laid early in 

 October on the food-phnt of the insect. They are of no 

 direct use to the ants, yet they are not left where they 

 are laid, exposed to the severity of the weather and to 

 innumerable dangers, but brought into their nests by the 

 ants, and tended by them with the utmost care through 

 the long winter months until the following March, when 

 the young ones are brought out and again placed on the 



