A. F. Blakeslee 23 



Q.'s we have a mortality of 6*8 °/^ in Q.'s against 0'7 °/^ mortality in 

 normals. Whatever the figures used, the infected plants are seen to 

 be less likely to survive than normals. As will be noted later, the 

 per cent, of germination of Q.'s is lower than that of normals, hence 

 the final records fail to indicate the total amount of seed infection. 

 I'he breeding evidence shows, however, that the Q. infection is carried 

 by the female gametes and affects at least 79 °/^ of the seed produced 

 by Q. parents. 



(6) Investigation of Tiuo Field-infected Plants. 



In the 191G field cultures two plants (A and B), which had become 

 spontaneously infected and which showed the infection in different 

 degrees in individual branches, were chosen for detailed study. The 

 problem was to ascertain if any relation existed between the pro- 

 portion of Q. offspring and the strength of the Q. character measured 

 by the relative number of spines on the capsules from which the 

 seedlings were derived. A smooth capsule was graded 0, and one fully 

 armed was graded 4 ; 1, 2 and 3 were intermediate grades from very 

 slightly spined to a condition with spines somewhat reduced below 

 normal. Final records were taken of the potted plants between four and 

 five months after planting. A considerable number of individuals were 

 not graded on account of late germination, or on account of doubtful 

 determination at the time it was necessary to clean out the green- 

 house for other cultures. If such doubtful plants had been retained to 

 a recordable size they would probably have increased the percentages 

 of Q.'s. All plants that germinated however, have been included in 

 figuring the percentages of germination. The capsules of plant B 

 were all open pollinated, those of plant A were part open pollinated 

 and part pollinated by hand. Tables III and IV (p. 38) give details for 

 the two plants, and Table V (p. 34) gives summaries. Although some 

 individual inconsistencies occur, it will be observed that the capsules 

 which show evidence of infection give a higher percentage of Q. seedlings 

 and a lower percentage of germination than capsules which appear 

 normal. 



A number of the capsules of plant A showed unequal distribution 

 of spines on the four valves of the type shown on PI. IV, fig. 7. Seeds 

 from individual valves were sown separately with the result shown in 

 Table VI (p. 34). Valves A and B form one carpel, and C and D form 

 the other, of the two-celled ovary. In some cases only a part of the 

 seeds was sown separately from the individual valves, and therefore 



