1906.] in Albinoes and Pigmented Animals, etc. 113 



(Series 1) is not so refined as Method B (Series 2), and partly to the fact 

 that in Series 1 a certain number of experiments in which the solution was 

 used on the second, fifth, and seventh days after preparation are included in 

 the mean results, while fewer of such experiments are included in the second 

 series ; the reason for the operation of this latter influence is given infra, 

 p. 113. That the ratio of the two series should be in the same direction 

 is corroborative proof of the truth of each. 



One possible source of error, arising from a want of complete homogeneity, 

 remains to be considered. It will be seen from an inspection of Tables II 

 and IV, or of Table VI, that the I solution, when of seven days' standing 

 after its preparation, was injected into only one pigmented rabbit (43) but 

 into three albinoes (40 to 42), and that the dose for the pigmented animal is 

 very small. It is possible that had another two pigmented rabbits been used, 

 the mean dose of the solution of this age would have been raised for the 

 pigmented animals. The same consideration holds for the J solution on the 

 second day after its preparation ; for only one experiment was performed on 

 a pigmented individual (57), and two on albinoes (53 and 56). But it is 

 obvious from a review of the means of these two solutions at other ages and 

 of the other solutions, that had the number of pigmented and albino 

 individuals been more nearly equal in these particular experiments, the 

 mean result would still have been higher for the albino and the ratio would 

 have been near that arrived at. That it would have been so is rendered all 

 the more certain by the fact that the ratio of resistance of albino and 

 pigmented animals is increased as the age of the solution increases ; this fact 

 alone explains the large difference between the albino and pigmented races 

 in these two experiments, i.e., those of the I and J solutions of seven and of 

 two days' standing. 



The greater resistance of the albinoes is graphically shown in fig. 1, 

 where the upper line, i.e., line of larger dose is the albino line. Cp. p. 117. 



(B) The Relative Resistance of Albinoes and Pigmented Animals to Nucleo- 

 Proteids derived from the Two Alternative Sources. Tables VI and VII. 



The results arrived at above show that albinoes are more resistant to 

 injections of nucleo-proteids than are pigmented individuals, and that this is 

 the case when the nucleo-proteid is derived from either pigmented or albino 

 individuals. The experiments, however, enable us to ascertain whether 

 albinoes and pigmented animals are more resistant or less resistant to 

 nucleo-proteids derived from their own source, or from the alternative 

 source. For, by comparing the mean results (p. 115) of injecting albinoes 

 with " albino " nucleo-proteid with those obtained by using " pigmented " 



