TRANSACTIONS OF SECTION I. 877 



we have the physiological basis of light arc! in the qualify of the impulse the 

 physiological basis of colour. I consider that the quality of the impulse varies 

 with the wave-length of the light causing the impulse. 



Cases of colour-blindness may be divided into two classes, which are quite 

 separate and distinct from each other, though both may be present in the same 

 person. In the first class there is light as well as colour loss. In the second 

 class the perception of light is the same as the normal-sighted, but there is a 

 defect in the perception of colour. In the first class certain rays are either not 

 perceived at all or very imperfectly. Colour-blind individuals belonging to the 

 second class can be arranged in a series. At one end of the series are the 

 normal-sighted, and at the other the totally colour-bliud. I have classified 

 the colour-blind in accordance with the number of primary colours which lliey 

 see in the spectrum. If the normal-sighted be designated hcxachromic, those 

 who see five colours may be called pentachromic : those who see four, letra- 

 cliromic ; those who see three, triehromic ; those who see two, dichromic ; and 

 the totally colour-blind, monocbromic. There are many degrees included in the 

 dichromic class. There may or may not be a neutral band, and this is widest in 

 those cases approaching most nearly to total colour-blindness. The tests 1 use 

 are three in number: (1) Lantern test; (2) Classification test ; (3) Spectrum test. 

 In all these tests the examinee is required to know the names of the primary 

 .colours — red, yellow, green, and blue, and matching is not employed. In the 

 spectrum test the examinee is required to point out the commeueement and 

 termination of the spectrum, designate the various colours, and show by a special 

 apparatus the size of the different portions of the spectrum which appear to him 

 monochromatic. 



5. Jifijort 011 the Electrical Phenomena and Metabolism o/'Arum Spadices, 



See Reports, p. 463. 



6. The Constitution of Lecithin and other I'hosphatives. 

 By Dr. Hugh MacLean. 



Lecithin used was obtained from the firm of T. I). Eiedel, Berlin, and is sold by 

 this firm under the trade name of ' Lecithol.' This lecithin was split up by means 

 of boiling for different periods with a solution of methyl alcohol saturated witli 

 I3a(0n)„: the products of hydrolytic decomposition were then separated off 

 and the choline obtained in as pure a state as possible in the form of choline 

 chloride. This choline chloride was precipitated by platinum chloride and tlie 

 double salt of chlorine platinum chloride obtained ; latter was washed, dried, and 

 weighed, and the amount of choline found was then calculated. In no case did 

 the amount of the double salt obtained correspond to more than 80 per cent, of 

 the theoretical amount calculated on the N present, and in a series of about fifteen 

 experiments the actual average result was only 77';5 per cent. 



This loss of over 20 per cent, is accounted for chiefly by tlie fact that 



(a) Platinum chloride does not completely precipitate choline even in con- 

 centrated solution ; there is a loss of anything up to 10 per cent. 



(h) Part of the N remains in the insoluble residue obtained after boiling the 

 lecithin. This varies from 6 to 10 per cent, of the total N. 



(c) Small losses due to decomposition of choline resulting in the production of 

 volatile products; presence of traces of impurities retarding precipitation ; slight 

 losses in general manipulation. 



Thus it may be assumed that the above ' lecithol ' contains practically all its 

 N in the form of choline. 



In lecithin obtained from heart-muscle, however, in which the proportion of 

 N to P was almost exactly as 1 : 1, not more than 40 per cent, of the theoretical 

 amount of choline platinum chloride could be obtained when heated iu the same 



