594 



Scientific Proceedings, Uoyal Dublin Society. 



into two groups as regards the Xes, and these again into two others as 

 regards the Fs, thus : — 



The expectation is again in 



Thus there should be 5 blacks : 3 agoutis, 

 accordance with the experimental results.' 



XX ,, ,X' X 



^^, the progeny of y y. 



as regards the JTes, and these again into two others as regards the Fs, 

 thus : — 



Constitutions. Expected colours. 



X'xYy black 



X! X y y black 



XxYy agouti 



X X y y black 



Mated with tortoise, the progeny of y Ti^ should split into two groups 



Relative numbers expected. 

 1 

 1 

 1 

 1 



Thus there ought to be 3 blacks : 1 agouti. Again, the expectations are 

 in accordance with the experimental results.^ 



It will be well to set down these three experiments in tabular form, so as 

 to compare the expected with the actual results : — 



Results of mating agouti-black with : — 



(1) Agouti-black.^ (2) Heterozygous-yellow.' (3) Tortoise.* 



Agouti 



Black 



Agouti-black 



Relative 

 numbers 

 expected. 



3 



7 

 6 



Actual 

 results. 



39 



107 



74 



Pielative 

 numbers 

 expected. 



3 



Actual 

 results. 



33 

 69 



Relative 

 numbers 

 expected. 



1 



Actual 

 results. 



15 

 51 



As already mentioned, the results got by mating the other group 

 heterozygous for two pairs of factors, y y (li^^ No. 28), are less satisfactory, 

 for the reasons that this group was not always clearly distinguished from its 



1 Journal of Genetics, vol. ii, p. 232. -/«A p. 232. ^Ibid.f.2Z\. ^Idid.y. 232. ^ Hid. y. 232. 



