Vererbung, Variation, Mutation. 131 



332) Weutworth, E. N., The Segregation of Fecundity factors in Dro- 

 sophila. In: Journ. of Genetics, Vol. III, Nr. 2, S. 113—120, 1913. 



A male and female Drosophila gave 126 offspring. Four pairs of these were 

 mated, (1) of small weak flies, (2) of large vigorous flies. (3) and (4) of medium 

 size and vigor. The offspring of each were inbred for eight generations. The 

 first pair gave an average brood of 29.5, the different generations ranging from 

 means of 35.8 to 24.6 with no case of more than 60 in a brood in a total of 

 115 broods. The second pair (large and vigorous) gave a mean of 135.8, the 

 eight generations ranging from means of 141 to 128; actual broods (among 70 

 broods reared ranged from 94 to 180. There was no lack of fertility in the later 

 broods. The medium lines segregated into lines of high, moderate and low fer- 

 tility. It is therefore concluded that fertility is due to segregable factors, of 

 which there are probably several which have a cumulative effect when combined, 

 and that loss of fertility on inbreeding is not a consequence of inbreeding, but 

 of the segregation of strains of low fertility. When high and low lines were 

 crossed, the male does not influence the fertility of the female with which he 

 pairs, though Ins influence is seen in later generations. Doncaster. 



333) Todd, C, On the recognition of the Individual by haemolytic 

 methods. In: Journ. of Genetics, Vol. 3, Nr. 2, S. 123—130, 1913. 



A Short summary is given of our knowledge of Immunity Reactions and of 

 the test of phylogenetic relationship by precipitin methods. The phenomenon of 

 haemolysis is then considered more fully; if, for example, a rabbit is injected 

 with red corpuscles of the ox, its blood develops a „haemolysin'" which dissolves 

 ox corpuscles but not those of other species. By keeping the haemolytic serum 

 in the presence of the foreign corpuscles at 0*^ C, the haemolysin is removed by 

 the corpuscles. If an animal is injected with corpuscles of several different spe- 

 cies, and when the serum has become haemolytic it is left at 0*^ in presence of 

 corpuscles of one of these species, the haemolysin for this species becomes exhau- 

 sted, but those for the other species remain. It was then shown that corpuscles 

 of another individual of the same species produced a haemolysin, and every in- 

 dividual (apart from close relatives) appears to have distinct blood-properties. 

 This was further tested thus. Over sixty cattle had been injected with blood of 

 other cattle; a mixture of all their sera was made, and exhausted with the 

 corpuscles of one ox. When tested on 110 different cattle, the mixture was pow- 

 erfully haemolytic for the corpuscles of every one, but without action on 

 those of the individual for which it had been exhausted. By this method, there- 

 fore, corpuscles of any individual can be recognised, and it was found that when 

 injected in quantity they disappear from the circulation in 4 — 7 days, after 

 which the serum becomes haemolytic. As regards relatives, it was found that 

 when a cow and her calf were tested, exhaustion of the serum with corpuscles 

 of the calf removed the haemolysin for the calf only, while exhaustion with the 

 cow's corpuscles removed the haemolysin for both cow and calf. In the case of 

 a family of sheep, (father, mother, 3 lambs) one lamb's corpuscles resembled 

 those of the mother, those of the other two, the father. Evidence is given that 

 other tissues have similar individual characters. Doncaster. 



334) Bond, C. J., Some points of genetic interest in regeneration of 

 the testis after experimental orchectomy in birds. In: Journ. of Ge- 

 netics, Vol. III, Nr. 2, S. 131—139, 2 Tai, 1913. 



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