226 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



In the examination of the codfish, made by Dr. Parker, 60 out of 100 

 individuals had the right nerve dorsal. Table VII shows a similar result 

 for several selected matings of different sorts. Comparing this table 

 with Table I, where the results of the first generation of trout are tabu- 

 lated, a similarity is found with the conditions observed in that species. 

 The range of variation in the percentage of rights is greater in the case 

 of the cod than in the trout. Lot D, 1901, is specially notCAvorthy. 

 With both parents lefts, there is among the young an excess of rights 

 instead of lefts, as might be expected. From the similarity of results 

 in the two species, the conclusions which were drawn in the case of the 

 trout are made more certain. Selective breeding again fails to bring 

 out any evidence that either condition is hereditary. 



TABLE VII. 



Results of Selected Matings in the Codfish 



(Gachis morrhua L.). 



Results oe Investigation of the Chiasmata in Monstrous 

 Specimens op Salvel'mus fontinalis. 



Double monsters among trout fry are of common occurrence. These 

 vary greatly in the degree and kind of malformation. The specimens 

 used for this investigation varied from those having two heads and 

 one body to those with heads and bodies entirely distinct but with 

 a yolk sac in common. For couveiiieuce the individuals have been 

 placed in four groups. 



