396 



NATURE 



[December 5, 19 12 



and tliat the animals, aided by their sense organs, 

 forage for food. In order to show the great activity 

 of the phyto-plankton in forming organic matter. Prof. 

 Moore mentioned that he had found the sea-water 

 10 be more alltaline in August than in April. He 

 attributed this change to the removal of carbon dioxide 

 from the water. When one considers the great bulk 

 of water concerned, the change in reaction must mean 

 an enormous synthesis of organic compounds. 



Prof. Fil. Botazzi added that the dissolved organic 

 nitrogen in sea-water is not sufificient to nourish the 

 animals, and that sea-water is almost neutral in 

 reaction. 



Dr. W. J. Dakin pointed out that plankton coUec- 

 lions did not necessarily contain all the particulate 

 food matter contained in the sea. Prof. Putter had 

 said that food was often absent from the alimentary 

 canal, but this might be due to the rejection of food 

 after the animal was caught. Dr. Dakin had fre- 

 quently found food in the alimentary canal. He be- 

 lieved that although some animals may live on dis- 

 solved organic matter, others certainly ingested parti- 

 culate matter. 



Prof. Leonard Hill, F.R.S., spoke about the effect 

 of high pressures of water on living tissues. Frogs 

 can survive exposure to pressures of 300 atmospheres, 

 but at 400 atmospheres their muscles become opaque 

 and disorganised. Bacteria are killed when the pres- 

 sure reaches 3000 atmospheres. Prof. Dofiein pointed 

 out that protozoa can live on dissolved organic matter, 

 and that digestion causes the solution of all foods 

 before they are absorbed. Dr. F. A. Dixey, F.R.S., 

 stated that insects can construct organic substances 

 from air, and hence sea animals mav possibly form 

 organic material from simple dissolved constituents. 

 Dr. N. Annandale described the effect of food in alter- 

 ing the colour of a form of hydra from Bombay. When 

 placed in an aquarium it takes food, and the colour 

 changes. Prof. A. Dendy, F.R.S., considered that all 

 work done on sponges can be discounted because they 

 are usually mixed colonies of plants and animals. 

 Therefore some of the experiments described by Prof. 

 Putter ought to be repeated with other animals. 



The third discussion, on the relation of mind to 

 body, was preceded by a paper by Prof. Max Verworn 

 on the physiological basis of memorv and abstrac- 

 tion. In this paper he stated that nerve cells increase 

 in size by use, and that the strength of the nerve 

 impulse depends on the size of the cell body. Thus a 

 series of nerve cells which had not been used should 

 act as a block by causing a gradual decrease in the 

 strength of the nerve impulse until the impulse 

 becomes too weak to pass from one cell to another ; 

 whilst a series of well-exercised cells should increase 

 the strength of the impulse. Nerve impulses should 

 therefore tend to be propagated along more frequented 

 paths. 



Prof. R. Latta opened the discussion by contrasting 

 the Parallelist and -'Xnimist points of view. The former, 

 recognising two independent systems which correspond 

 point for point, involves an extension of the mechani- 

 cal hypothesis to mind, in utter disregard of the fact 

 that the mechanical hypothesis is founded on the neces- 

 sity of excluding everything mental from the physical 

 system. The latter insists on the recognition of a 

 teleological factor in organism and mind, placed 

 entirely outside the mechanical system, and requiring 

 an endless series of miracles. His conclusion was that 

 mind cannot be entirely separated from matter, and 

 that the distinction between the physical and the 

 psychical, the mechanical and the teleological, is a dis- 

 tinction within one and the same system. 



Sir T. .S. Clouston dealt with the effect of diseased 

 conditions, thus emphasising the intimate connection 



NO. 2249, VOL. 90] 



of the structure and chemistry of the brain with the 

 mental processes. 



Dr. J. S. Haldane, F.R.S., emphasised that it is 

 impossible to separate mind from the bodily structures, 

 nor can physiological processes be separated from 

 physical and chemical laws. His belief is that the body 

 properly understood is the mind, and that the physical 

 sciences treat of a one-sided aspect of reality. The line 

 of development is that in which the organic extends so 

 as to include the inorganic. 



Dr. H. J. Watt maintained that before the problem 

 of the mind-body relation can be raised, it is necessary 

 to form a properly classified catalogue of psychological 

 states, and to determine whether some satisfactory 

 correlation cannot be found among known or possible 

 physiological processes. He urged that the facts 

 adduced by McDougall in favour of interaction are 

 really compatible with the broader views of parallelism. 



Dr. C. S. Myers held the most tenable hypothesis to 

 be that of parallelism between neural and mental 

 processes and products, coupled with the realisation 

 that the same difficulties which beset the explanation 

 of the course and nature of mental processes occur on 

 the neural (physiological) side. 



Prof. Geddes demonstrated by a diagram that the 

 opposing views are really two aspects of the same 

 thing, depending on whether the attention is fixed on 

 the influence of the organism on the environment, or 

 that of the environment on the organism. Prof. F. 

 Geddes, F.R.S., and ProL E. H.' Starling, F.R.S., 

 each considered that the discussion was premature, 

 and they agreed with Dr. Watt that psychology must 

 advance further before the subject can be profitably 

 discussed. Prof. Leonard Hill, F.R.S., said that, in 

 spite of our inability to reach a conclusion, the human 

 mind seems prone to consider its relation to its en- 

 vironment, and that the present discussion was in 

 deference to this propensity. 



Two interesting demonstrations were given. Prof. 

 Heger showed some kinematograph films illustrating 

 the beating of the tortoise heart with the effect of 

 poisons upon it, and the movements of the circulation 

 in Crustacea and the frog. 



Prof. Leduc illustrated the effect of diffusion by 

 placing drops of a watery suspension of Indian ink 

 on a salt solution. He believes that cells represent 

 dynamic centres which, by centrifugal and centripetal 

 forces, produce the various appearances which we 

 ascribe to cell structure. 



Prof. F. Gotch, F.R.S. : In the dark adapted eye 



the peripheral portion of the retina is more sensitive 



than the fovea ; red vision extends some distance 



beyond the fovea, but green is confined to it. A 



green light falling outside the fovea is recognised as 



j a white glare. Owing to the peripheral portion being 



I more sensitive, a feeble light disappears when it is 



I fixed. Hence, after a light has been discovered at 



night, to distinguish white from green, night-glasses 



must be used in order to raise the luminosity above 



the threshold for the fovea. 



Dr. Edridge Green criticised for three reasons the 

 report of the Departmental Committee on Sight Tests. 

 The retention of the wool test, the form of lantern, 

 and method of flicker photometry recommended were 

 condemned. In the subsequent discussion all who 

 spoke condemned the wool test, but the form of lantern 

 and flicker photometry were efficientlv defended. 



At one time an interesting discussion seemed im- 

 minent. After a paper by Prof. Hamburger on 

 phagocytosis. Prof, .\sher read a paper on cell per- 

 meability. The former demonstrated the ingestion 

 of carbon bv leucocytes, and described the effect of 

 certain substances on the rate of phagocytosis. Some 

 of these substances, he said, acted because of their 



