192 THE MENDEL JOURNAL 



by the low form of comb ; the serration is not pro- 

 nounced, the teeth tend to run together, and the 

 apices of the teeth are acute. In our Group 2 we 

 find the type iUustrated in Dr. Pearl's Figs. 88 and 96, 

 and in our Fig. 2, and around them those shown in his 

 Figs. 11, 64, 67, 76, 77, 78, 86, and 90 fluctuate 

 in one direction or the other. This group is characterised 

 by having the teeth somewhat in the general form 

 of a parallelogram, they tend to be indented or 

 spurred, and their apices are sub-acute. In our 

 Group 3 the type is illustrated in Dr. Pearl's Figs. 

 50 and 92, and in our Fig. 3, while a loAver form of 

 comb of the same type is illustrated in his Figs. 24 

 and 63. The group is characterised by its well defined, 

 triangular large teeth with acute apices. Our Group 4 

 is shown in its typical condition in Dr. Pearl's 

 Figs. 13 and 22, and in our Fig. 4, with his Figs. 7, 

 71, and 73, and others fluctuating around them. This 

 group is characterised by its well defined, somewhat 

 long-narrow, triangular-shaped teeth with sub-acute or 

 obtuse apices. A form of comb like that figured in 

 Dr. Pearl's Figs. 69 and 85 and some others are probably 

 to be regarded as heterozygous ones, and carrying 

 some two or more of the above four groups. 



We must once more intimate that we do not commit 

 ourselves to the positive statement that these four 

 groups are actual gametic entities ; experimental breeding 

 alone can decide that. But we do assert that Dr. Pearl's 

 figures appear to us not to form a continuous series 

 without some perceptible gaps, and that it is possible 

 to beheve at least four distinct gametic types exist 

 within the class of single comb in the Barred Plymouth 

 Rock hen. In the investigation of such problems 

 the only method that can be of any avail is that of 

 the Mendelian. We must, for instance, take the two 

 most diverse types, such as our Group 1 and Group 3, 

 and breed them together. In other words, we should 

 endeavour to see whether such a comb as that shown in 

 Dr. Pearl's Fig. 10 or 36 clearly segregates from such a type 

 as that shown in his Fig. 50 or 92. When that has been 

 adequately attempted, we shall then be able to claim a 



