No. 568] X CAP SELL A BURSA-PASTOEIS ARACHNOIDEA 215 



the first, was classified as a rhomboidea. At the present 

 time, a photograph of the young roset confirms this 

 classification. But two climax leaves, which, in the 

 earlier part of these experiments, were deemed suffi- 

 cient, show that the sinuses do not quite reach the midrib 

 (Fig. 12). Unfortunately, Shull, in the description of 

 his No. 054.28, 16 does not mention this point, though he 

 does point out that "the later rosette-leaves had some 

 of the secondary lobes acutish, but not elongated." In 

 the older climax leaves, even of a homozygous rhom- 

 boidea, I find that the secondary lobes disappear. Shull, 

 in the description just referred to, is so specific as to the 

 typical rhomboidea character of the heterozygote that I 

 have hesitated to classify the heterozygotes and the homo- 

 zygotes. But the homozygotic rhomboidea, obtained as 

 the extracted recessive of a selfed plant of the supposed 

 zygotic constitution BBNn, always has sinuses which 

 reach the midrib. In other combinations, also, one can 

 distinguish between BB and Bb by the relative depth of 

 the sinus. For the present, then, we will rely upon this 

 character. In the case under discussion (26,612, the off- 

 spring of 8,212#ittP3, guarded) there were among the 

 39 plants 6 which clearly were simplex, the heterozygotic 

 rhomboidea was represented by 22 individuals, and the 

 homozygotic rhomboidea by 11 individuals, the calculated 

 ratio being 9.75 : 19.50 : 9.75. The percentage of simplex 

 is far too low, 15.4 per cent., instead of 25 per cent., but, 

 considering the small number of individuals concerned, 

 the total outcome is fairly satisfactory. It is almost un- 

 necessary to add that in this, as in other cases, the off- 

 spring of the various plants is being tested as fast as 

 time and facilities permit. 



Type 4. — Having shown the presumable correctness of 

 our supposition as to the zygotic constitution of the initial 

 plant (BbNn), as far as the presence, appearance and be- 

 havior on brooding f si»i}>h>r, rhomboidea and attenuata 

 are concerned, there remains to identify the major group of 

 combinations which, in a simple di-polyhybrid, constitutes 



