366 SECTIONAL TRANSACTIONS.— 1). 



those frequenting the neighbourhood of water in heavy shade (e.g. 0. palpalis) and 

 those found in more open bush-country (e.g. G. morsitana). It is misleading to talk 

 of ' The Tsetse-fly problem ' ; there are two, and the problems of attacking each 

 group differ greatly. 



One of the greatest problems is whether big game is a danger, since Trypanosomes 

 found in them are apparently indistinguishable from those causing Sleeping Sickness. 

 The problem can only be solved by e.xperiment on a volunteer, but there is evidence 

 that prolonged sojourn in an antelope renders the Trypanosome less able to live in 

 man, so that big game may be beneficial rather than harmful. 



20. Discussion on The TroAning of a Zoologist. 



Prof. J. H. AsHwoRTH, F.R.S., Prof. W. J. Dakin, Prof. Julian 

 Huxley. 



21. Joint Discussion with Sections H and J on Heredity in its 



Physical and Mental Aspects. 



Dr. C. S. Myers, F.R.S., Prof. R. Ruggles Gates, Mr. R. N. 

 Salaman, Mr. T. Cooke, Prof. Julian Huxley, Dr. F. A. B. Crew. 



Dr. C. S. Myees. — Heredity has b.3en viewed from two standpoints — the physical 

 and the psychological. According to the former, definite units of ' behaviour ' exist, 

 and these are separately localisable in different structures within the germ-cells, much 

 as various mental functions are commonly supposed to be localisable in different regions 

 «f the cerebral hemispheres. Adoption of the psychological standpoint, on the other 

 hand, has resulted in vague and otherwise unsatisfactory analogies being drawn between 

 heredity and memory. It is my object here to suggest that other and more valuable 

 psychological considerations may bo utilised, and that the final solution of the nature 

 of heredity lies in a combination of both standpoints. 



The physical standpoint must naturally be confined to i, purely mechanistic 

 explanation. But this can only be one aspect of the entire truth. What is foimd in 

 mind must also occur in life. ]31ind mechanism is a mere abstraction from the who'- . 

 The purely mechanical reflex is rarely a separate entity in the intact organism. Lo, 

 too, instinct and genius are inseparable (save by abstraction) from intelligence. 

 Orderly, purposeful direction, however rudimentary, is universal in the creation of 

 the nevi'. 



Because a certain area of the cerebral hemisphere must be intact in order that a 

 certain kind of consciousness may occur, it does not follow that that area is the seat 

 ef that kind of consciousness. Wo are only justified in concluding that a necessary 

 soadition for a special kind of consciousness to appear is that the corresponding 

 nervous processes must pass through a special area of the cortex. The localisation 

 of inherited qualities in chromosomes may have merely a similar implication. 



At all events what is obviously inherited seems something more akin to mind 

 than to matter ; the functioning of the whole and the interrelation between parts, 

 general orderliness, and direction seem at least as important as a narrow material 

 localisation. It is in the persistence of these rather than in its identical substance 

 that the ' immortality ' of germ-plasm consists. 



Here enters the difference of attitude between the physicist and the psychologist. 

 The physicist is generally content with analysis of a complex body into elementary 

 ones. The psychologist more frequently observes that identical elements, e.g. the 

 notes of a melody, may be differently combined to yield quite a different melody, 

 and that the same melody may nevertheless be evoked from a set of quite different 

 notes by transferring it into another key. But the psychologist goes beyond the 

 conclusion that the properties of a whole depend on the H7id of combination of the 

 parts ; he insists that in the living organism the parts are themselves altered by 

 separation from the whole, and that within it they depend on interrelation between 

 parts of the system to which they belong, and even more generally on the configuration 

 of systems of wider and wider complexity. Thus formal, as well as material, bases of 

 heredity must be (as, indeed, they are being) taken into consideration. 



The controversy in regard to gradation as opposed to sudden changes in inherited 

 characters may gain some help from the fact, well recognised in psychology, that 



