466 



NATURE 



[September 15, i8q2 



"The Limits of Animal Intelligence," 



It is with much pleasure that I have read Prof. Lloyd 

 Morgan's letter, wherein he tells us that "the power of cognizing 

 relations, reflection, and introspection" appears to him to mark 

 a " new departure" in the ascending scale of psychical activities. 

 His term, " feeling of awareness of certain relationships," is new 

 to me, however, and seems to demand a further distinction. I 

 am generally aware, in a vague way, of what I may be doing — 

 that is to say I have a certain consciousness of it. But every 

 now and then I find that I have done, without consciousness, 

 things which I could not have done without the exercise of my 

 Fensitive faculty, or without the guidance of bodily movement, by 

 that faculty. 



I most cordially concur in the Professor's desire that the inves- 

 tigations to which he refers should be accompanied by " calm, 

 temperate, and impartial discussion " founded on observation 

 and experiment. I, as well as Prof. Lloyd Morgan, have long 

 carried on such observations and experiments, and it is 

 on them that are founded what I have written on "Our 

 lower and higher mental powers" in chapters xiv. and xv. 

 of my book^ "On Truth." To them I may perhaps be 

 permitted to direct the Professor's attention, since he is en- 

 gaged with a work on Comparative Psychology. I have 

 as little wish to dogmatize as has Prof. Lloyd Morgan, and am 

 perfectly ready and willing to recognize the true rationality of 

 any animal whenever I obtain evidence thereof. My assertion 

 of the exclusive rationality of man has been represented as due 

 to other causes than what I deem to be the weight of scientific 

 evidence. Such is an utter mistake. To admit that animals 

 possess intellect would neither be repugnant to my feelings nor 

 conflict with any other of my convictions. As yet I hold all 

 animals to be irrational, simply because I have met with, in them, 

 nothing inexplicable by what the Professor calls "simple aware- 

 ness" and what I call related feelings. All prejudice should 

 indeed be eliminated from scientific inquiry, but such can hardly 

 be the case with anyone who starts from an a priori "stand- 

 point of evolution " in the sense that he holds discontinuities in 

 nature — real " new departures " — to be impossible. 



The Professor says : " In conclusion I must be allowed to say 

 that the phrases ' differences in kind ' and ' differences in degree ' 

 savour somewhat of mere Academic discussion." Neverthe- 

 less there really are differences of kind, and such differences 

 are theuiselves different in kind from mere differences of degree. 

 He would, of course, allow that the difference between the 

 Binomial Theorem and the Bouquet of Chateau d'Yquem is 

 one " of kind," as also that between solving the Pons asinorum 

 and riding Equus asinus. I am convinced there are also 

 psychical differences of kind, and I have become so convinced (in 

 spite of having started with a contrary opinion) through experi- 

 ments and observations. 



St. Georgk Mivart, 



Hurstcote, September 6. 



The Theory of the Telephone. 



In a paper in this month's Phil. Mag. I ventured to publish 

 an explanation of the fact that in the telephone it is necessary 

 for the diaphragm to be situated in a permanent magnetic 

 field. 



Since then my attention has been called to a paper {The 

 Electrician, Feb. ii, 1887, p. 302) by Mr. Oliver Heaviside, 

 in which he has given a very complete theory of the question 

 at issue. 



I hasten to express my regret that I had not met with this 

 paper in time. Fred. T. Trouton. 



Physical Laboratory, Trinity College, Dublin. 



Crater-like Depressions in Glaciers. 



In the note on the St. Gervais Catastrophe (Nature of 



September i) I read that a crater-like depression had been 



iound in the Tete Rousse Glacier. As such depressions are 



quite exceptional occurrences in European glaciers, it may be 



of interest to note that I found several holes of a similar kind in 



the great Tasman Glacier in New Zealand. One of these reached 



— like the Tete Rousse one — apparently to the bottom, the 



others, which were from 150 feet to 300 feet deep, did not. The 



walls of these " craters " were not vertical but abjve only 45°, 



the incline increasing below. Till now I have considered these 



funnel-shaped depressions as immensely widened "Glaciermills," 



I Referred to oa p. 266 of Nature for July 21, 1892. 



NO. I 194, VOL. 46] 



but after the observation on the Tete Rousse it seems to me not 

 improbable that these holes on the Tasman were also originally 

 caused by subglacial collapse. 



R. VON Lendenfeld. 



CHOLERA : PREVENTION AND VACCINA TION. 



THE epidemic of cholera with which this country 

 is threatened seems likely to test very completely 

 the means for the prevention of its spread which have 

 been devised as the result of the extended experience of 

 some of the ablest hygienists. The working out of the 

 history of an epidemic disorder must necessarily be ex- 

 tended over a prolonged period of time, for it is depend- 

 ent on the researches not only of the clinical observer, 

 but of the pathologist and the bacteriologist and of those 

 who devote themselves to the difficult study of the march 

 of epidemics. The development of such researches is 

 closely allied to the advance of science generally, and 

 although there is at any one period a large admixture 

 of "fashion" in the opinions held by experts, yet in time 

 this fades, and the truth is established. It cannot be too 

 clearly stated that the best measures for the prevention 

 of an epidemic disorder can only be devised when we pos- 

 sess an accurate knowledge of the infective agent of the 

 disease (bacillus or not, as the case may be), of its life- 

 history, of its varying degrees of virulence, and the mode 

 of entrance into the body, of the conditions under which 

 it multiplies, and of the changes which it produces in the 

 human body. 



In the case of cholera our knowledge is not yet com- 

 plete. Clinical observers many years ago showed that the 

 infective agent was present in the peculiar evacuations 

 passed by the cholera patient, and it was further found 

 that these evacuations were the means of contaminating 

 the water supply of a locality, and so causing the spread 

 of the disease in the community. These two facts have 

 been established beyond doubt. The exact nature of the 

 living infective agent is not, however, so well ascertained. 

 It was in 1884 that Koch described the Vibrio Cholerce 

 .^.y/flZ/V^ as constantlypresent in the evacuations of cholera 

 patients, but he was unable to prove that it was the cause 

 of the disease, owing to the insusceptibility of animals to 

 cholera. It was shown that the vibrio was present also 

 in the intestinal walls, but it was never found in the 

 organs of the body. The work of subsequent observers 

 has brought forward fresh facts of importance. It is now 

 known that the cholera vibrio (the comma bacillus) is 

 allied to several other forms which are pathogenic, and 

 that there are several varieties (perhaps twelve) which 

 have been described by Dr. Cunningham. The cholera 

 vibrio is also known to vary greatly in virulence ; it is so 

 susceptible to its surroundings that a slight change will 

 diminish its activity and certain conditions will increase 

 its virulence. One method of increasing its activity is by 

 passing it through a series of animals (guinea-pigs) ; after 

 a certain time the vibrio becomes extremely active and 

 will kill animals very quickly, it is said in even eight hours. 

 With these virulentculturessymptoms have been produced 

 in animals closely resembling those of Asiatic cholera ; 

 in the exudation of liquid into the intestines, in the 

 cramps, in the suppression of urine, and in the collapse 

 so well known in the disease in man. There are therefore 

 certain grounds for considering Koch's vibrio as the 

 cause of Asiatic cholera. But the question is not settled : 

 it is not as clear that the vibrio is the cause of Asiatic 

 cholera as that the bacillus anthracis is the cause of an- 

 thrax. The probabilities are greatly in favour of this pre- 

 sumption, but the slight doubt existing must be borne in 

 mind when the question of vaccination for cholera is to 

 be considered practically. The doubt that rests on the 

 vibrio as the cause of cholera may be stated shortly in 

 the fact of the existence of allied forms of bacteria which 

 j produce similar symptoms, such as the vibrio Metschni- 



