396 SECTIONAL TRANSACTIONS.— I. 



in assuming that there are three underlying fundamental sensations. There have 

 been numerous mathematical expositions of the trichromatic theory of colour-vision 

 which are correct from the mathematical point of view, but the physiological aspect 

 has been entirely overlooked. No two sets of observers have agreed on the three 

 variables. A different construction is required for each set of facts. 



As Parsons states: — 'The three components theory becomes less plausible the 

 more concrete the form it takes. We must therefore accept the theory as explaining 

 satisfactorily either the phenomena of after-images or those of dichromatic vision, 

 but not both.' It should also be shown that when complementary colours are com- 

 bined to make white the same proportions of the hypothetical sensations should 

 exist as in the white equation. This has not been done. Frank Allen finds that the 

 green of the spectrum appears as a simple sensation and not as if compounded of three 

 sensations. When we come to colour-blindness, we find important differences in the 

 white equation. It has been assiamed by many that anomalous trichromatics — that 

 is, those who put too much red or too much green in the mixture matching white — are 

 necessarily colour-blind, but this is not the case. Abney has classified the partially 

 colour-blind by calculating the amount of red or green above the normal which is 

 put in the equation, and also states that they do not agree with the normal white 

 equation. At the Board of Trade a hundred and fifty-four cases of partial colour- 

 blindness were tested by me on this point ; forty-seven of this number matched the 

 normal equation with normal simple white, ninety-two matched the normal equation 

 when luminosity of simple white was either reduced or increased, fifteen would not 

 match normal equation at any point of luminosity of simple white. It will be seen, 

 therefore, that over ninety per cent, matched the normal equation, either with the 

 normal simple white or when the luminosity of the simple white was either reduced 

 or increased. In each case an erroneous white equation was made as well. 



If we regard the colour-vision centre as arranged in a similar manner to the 

 spectrum — that is, one side being responsive to impulses caused by red light and the 

 other side to impulses caused by violet light, and the intermediate portions to orange, 

 yellow, green, and blue lights respectivel}' — we have a theory which will explain all 

 the facts, including those of Burch and Roaf. 



5. Prof. H. E. Roaf. — On the Threshold for Hue Discrimination of Normal 



and Hypo-chromatic Individuals. 



Friday, August 6. 



6. Joint Meeting with Section D {q.v.) for Papers on The Value of 



Tissue Culture in Biology. 



Demonstration of Microscopical Preparations by Prof. Ch. Champy. 



7. Sir Jagadis Chunder Bose, F.R.S. — The Action of Alkaloids and of 



Cobra-venom on the Pulse-beat of Plant and Animal. 



The life-mechanism of the seemingly impassive plant has hitherto been regarded 

 as quite different from that of the restless animal. The devising of suitable highly 

 sensitive apparatus has permitted the revelation of hitherto imsuspected life- 

 mechanisms within the plant. 



In the animal there are three striking reactions — muscle-contraction, conduction 

 in nerve, and the rhythmic pulsation of the heart with the circulation produced 

 thereby. 



Just as there are marked differences in the contraction of different muscles (cf. 

 the wing-muscles of the falcon and of the domestic fowl), so in the plant kingdom 

 we find a very active motile organ in mimosa while in the bean there is little or no 

 activity. Differential staining shows that the degree of activity runs just parallel 

 with the amount of a highly oxiclisable substance present in the motile organ. ' 



With regard to conduction, if suitable stimuli are used, rather than such violent 

 methods as knife-thrusts, there is a remarkable relation between conduction in plant 

 and in animal. In the plant, too, excitation takes place at the kathode at make and 

 the anode at break ; the passage of the impulse can be arrested, for example, by a 



