E. HiNDLP] 
265 
Observations on Breeding in relation to Melanism. 
The various colour varieties were isolated, and attempts made 
to produce pure strains, the results of which will be given in detail 
on a future occasion. It will be sufficient to say here that a pure white 
strain was easily obtained, but great difficulty was experienced in 
obtaining pure strains of the darker races. There seems no doubt that 
the method of inheritance is alternative, but whether associated with 
the sex or not is not yet decided. 
Conclusions. 
The interruption caused by the war has prevented these experiments 
being completed and the results obtained are insufficient to afford a 
reasonable explanation of the peculiar mode of sex inheritance in 
Pedieulus humanus which has come to light. It is difficult to explain 
the results of the experiments in the case of the third generation where 
apparently the same crosses (dd x $?) have produced pure d broods 
in two cases and a pure ? brood in one case. Whereas pure unpig- 
mented strains were readily raised, difficulty accompanied the attempt 
to obtain pure darkly pigmented strains. The method of inheritance 
in respect to pigmentation appears to be alternative. The author 
hopes to resume his investigations at the conclusion of the war. 
