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JOHN T. BUCHHOLZ 
eral categories, and the figures at the side indicate the number of embryos 
falHng within each group. 
It is to be expected that when the appearance of fusion is not very 
marked, as in many of the instances that were included in lot B, these 
double primordia will not all fuse to form single broad cotyledons. Many 
of them will form two distinct cotyledons in spite of the fact that they 
appeared to be fusing at an early stage. 
If we may assume that twenty-eight fusions will occur, an average of 
one ftision for every embryo in lot B, then the average number of cotyledons 
Fig. 6a. Diagrams illustrating the character of the five categories into which the em- 
bryos of Picea mariana (Lot B) were subdivided. The figures to the left indicate the 
number of embryos in each group. 
produced in lots B and C combined will be 4.10, which is still quite close 
to the value 4.17, the average of lot D. 
A study of Larix europaea gave very similar results. The material was 
secured at Dundee, Illinois, during the latter part of July 191 7. The cones 
had been poorly pollinated and very few good seeds were found in each cone. 
The quantity of material was thus quite limited but included material from 
two collections gathered about a week apart. The embryos are only slightly 
larger than those of Picea in the cotyledon primordia stage, as is shown in 
figure 19. 
The embryos were separated into lots in the same way as those of Picea, 
and the results are tabulated below. It is significant that the average 
number of primordia in lot C agrees quite closely with the cotyledon aver- 
age found in lot D, and that lot B has in this case an average of 0.55 primor- 
dia in excess of the number of cotyledons that it may be expected to produce, 
based on a comparison with lot D. However, considering the small num- 
