200 



SCIENCE. 



[Vol. XI. No. 27^ 



temperature-sense, as the changing of the position of the larva: at 

 different times of day indicates. Insects must be very insensitive 

 to pain, or a spider would hardly eat up its own leg just after it had 

 been cut off, as Forel observed. Ants are thus well supplied with 

 senses, and, though their actions are largely instinctive, some con- 

 trol over the co-ordination of these instincts undoubtedly exists. 



Another worker in the same field, Dr. H. C. McCook {Proceed- 

 ings of the Philadelphia Academy of Sciences, ^^^^xt iii. 1887), con- 

 tributes a note on the sense of direction in ants. The species is 

 the Formica rifa of Great Britain, and the observation was made 

 in Scotland. These ants build mounds as much as three feet high 

 and from six to seven feet in diameter at the base. From such a 

 mound, roads are seen to radiate. These roads are stained dark, 

 probably by the-action of the formic acid which the ants secrete ; 

 ■and the leaves and grass over which the road passes are worn 

 smooth by the constant action of innumerable legs. From one such 

 mound three roads radiated, and were traced to their termini, — 

 three oak-trees, on the branches of which were Aphides, the ' milk- 

 cows' of the ants. The directness of these roads was remarkable. 

 The first was twenty-one paces (about sixty-five feet) long, and 

 was almost perfectly straight from the nest to the tree. The sec- 

 ond was twenty-three paces (seventy feet) long, and varied less 

 than three inches from a straight line if measured from the nest to a 

 point within two feet of the tree, where an originally straight path 

 had been abandoned for a detour. The third road was thirty-four 

 paces long; for six paces it ran straight, then encountered an old 

 stump that caused a deflection, but then went directly to the tree, 

 across a foot-path, and, as it was, the deviation was not more than 

 three feet from a straight line. The straightness of these roads 

 cannot be attributed to chance ; and the fact that ants can see only 

 a little way off (and especially in this mass of bracken and other 

 plants) opens up a real problem as to the nature of a sense of 

 direction in ants. Dr. McCook adds the mention of the remarkable 

 feat of a Texas ant making an almost perfectly straight path 669 

 feet long, 448 feet of which ran under ground at an -average depth 

 of 18 inches. 



The Function of the Cerebrum in the Dog. — In his 

 last contribution to the physiology of the brain, the eminent physi- 

 ologist at Strassburg, Professor Goltz (Pflugcrs Archiv, 1888), 

 gives an account of a dog from which one entire cerebral hemi- 

 sphere had been removed. Here there was not, as some physiolo- 

 gists would expect, a paralysis and an anssthesia on the side op- 

 posite the injured organ ; but the action of the dog was quite 

 normal, only that he preferred the side controlled by the intact 

 hemisphere. This goes to show that in the dog one hemisphere 

 can to a large extent perform the functions for the entire body. 

 As a converse proof, if symmetrical regions are removed from both 

 halves of the brain, the result is a much more serious one. An 

 animal lacking both its frontal lobes had its intelligence much 

 diminished, was restless, constantly moving, could not feed itself, 

 could not hold a bone, and was a decidedly abnormal dog. A dog 

 with both its occipital lobes gone shows marked sensory defects, 

 but behaves much more normally than the former dog, thus indi- 

 cating that the part removed is of vital importance. 



A Suggestion for the ' Telepathic ' Theory. — Professor 

 Josiah Royce has an apt word to say in regard to the cases of 

 coincidence of a critical experience with a strong impression of 

 danger on the part of a distant friend, which some regard as evi- 

 dence of 'telepathy ' {Mind, April, 1888). He offers as a solution 

 of the many cases in which the evidence rests entirely on the word 

 of a reliable witness, that the memory is the subject of a hitherto 

 undescribed hallucination : it is an " instantaneous hallucination of 

 memory, consisting in the fancy, at the very moment of some excit- 

 ing experience, that one has expected it before its coming." As A 

 learns of the death of B, it suddenly and vividly occurs to him that 

 ■fee expected B's death, and had a distinct presentiment of it. The 

 belief might come with irresistible force, and acquire strength by 

 reflection. One such hallucination of memory is well known : the 

 feeling that an experience has been here before. Here we easily 

 recognize the illusion, because we know that we do not live our 

 lives twice ; but in the other case no such corrective is at hand. 

 If such .illusions occur, marked instances of them should be found 



among the insane. Two cases are cited, the one of a young girl 

 whose lover (so she says whenever any thing happens) predicted 

 every thing to her, — her removal to another asylum, a change of 

 physicians, and so on. The other case is that of a young man who 

 believes that all the events of asylum-life have been told to him in a 

 previous conversation. The news of the day is similarly antici- 

 pated. An interesting point in this case is, that the patient tells 

 that when these (imaginary) conversations occur he pays little at- 

 tention to them, but when the real occurrence takes place he vividly 

 remembers the former conversation. His memory for real events 

 remains quite good. Now that attention has been called to the 

 possibility of such illusions, normal instances of them should be 

 forthcoming. 



ELECTRICAL SCIENCE. 

 Cost of Electrical Distribution by Transformers and Secondary 

 Batteries. 

 The attention of electricians, both in this country and in Eng- 

 land, has been lately called to the relative values of continuous- 

 current and alternating-current distribution. In the discussion be- 

 fore the English Society of Telegraph Engineers and Electricians, 

 the majority of the speakers seemed to incline toward the alternat- 

 ing system, apparently relying to some extent on rose-colored re- 

 ports of the successful working of plants on' this side of the water. 

 There were several members, however, who spoke strongly in favor 

 of the continuous-current system ; and one of them, JVIr. Crompton, 

 has published figures of the comparative cost of installing ten 

 thousand 16-candle power lamps, burning simultaneously, using m 

 the first case the continuous-current system with storage-batteries ; 

 in the second, alternating-current transformers. 



With Secondary Batteries. 



Motive power, six i66-horse power sets=g96 horse-power at ;^8 i2s^ ■ ■ - .£^,700 



Dynamos 4.8oo 



Building to suit above 8,000 



Charging-main, 45 tons at ;£8o 3.6m 



Laying main in culvert 1,500 



Distributing-mains, iz,ooo yards at 16s. per yard • 9«6o° 



Service-bo.xes, 450 at ;£2 9°° 



Batteries, four sets of 50 cells each 8,640 



Regulating-gear 1,000 



Total £48,740 



With Alternating-Current Transformers. 



1,450 horse-power at ;£3 12s. per horse-power ;£' 2,500 



Dynamos and exciters 5,54° 



Buildings to suit above 11,000 



Charging-main 2,400 



Distributing-main, 12,000 yards at 14s. per yard 8,400 



Service-boxes, 450 at ;£2 900 



Regulating-gear 500 



Transformers, assuming one large one for two houses, 30D at £,-2~, 



(including fixing) 7,500 



Total jC48,740 



These estimates may be taken for what they are worth : they 

 probably give an approximate idea of the cost of different items. 

 The storage system of Mr. Crompton, however, is not a complete 

 storage system, such as will be used if secondary batteries become 

 much more economical than at present. The cells are not located 

 at some distance from the station, and charged by currents of high 

 electro-motive force : they are placed in the station, and are only 

 charged for a portion of the twenty-four hours, the plant remaining 

 idle during the remainder of the day. For short distances, such as 

 Mr. Crompton contemplates, this is possibly the best arrangement. 

 It would have been interesting if the running expenses of the two 

 systems had been compared, but the necessary data are hardly, at 

 the present time, available. 



Advantages of Electricity for Railroad- Work. — The 

 rapid advances of the application of electricity to street-car trac- 

 tion brings up the question whether we cannot in the near future 

 look to the displacement of the steam-locomotive by the electric 

 motor. The conditions of street-car and railroad work are differ- 

 ent : in the first, electricity is called upon to displace horses, an 

 extremely costly motive power; in the second, it must displace 

 steam. That it can economically replace horses has been shown 



