stout: pollinations in cichorium intybus 363 



appears to be no difference between heads that produce seed and 

 those that do not. The heads close and the petals wither as de- 

 scribed, and the mass of withered corollas break from the ovaries 

 and fall to the ground in about twenty-four hours in quite the same 

 manner. For a few days the young achenes show no differences, 

 but in the course of ten days or two weeks, those of self-sterile 

 and of cross-sterile pollinations become shrivelled and light- 

 colored, and are not closely packed in the head ; and such develop- 

 ment also occurred when the stigmas, stamens, and petals of 

 unopened flowers were shaved off with a razor, a procedure to 

 which a number of the parent plants of 191 2 were submitted in 

 testing whether parthenogenesis occurs in Cichorium as it does in 

 Taraxacum. 



In the later stages of seed development, it was in most cases not 

 difficult to distinguish the heads having viable seed nor difficult 

 to distinguish seeds with embryos from empty seeds. It may be 

 noted that as a single flower of Cichorium produces only one seed, 

 which is a somewhat conspicuous achene, the judgment of fertility 

 is simpler than is the case in plants which produce capsules with 

 numerous small seeds, some of which are nearly always empty 

 from various local physiological conditions not involving any 

 incompatibility between pollen and stigma. In determining the 

 result of pollinations, the tagged heads were inspected frequently 

 during the period of the ripening of seed. When a head matured 

 it was removed and the seeds carefully examined one by one, 

 and all that appeared to* contain embryos were placed in a seed 

 envelope together with the tag belonging to the head, while the 

 complete data were recorded on the envelope. The tags were 

 collected from all heads that produced no seed and in which there 

 was no apparent injury of branches. English sparrows and gold- 

 finches were frequent in the Garden and through feeding on the 

 seed interfered to some extent with the seed collection. In nearly 

 all cases their visits were confined to heads that produced good 

 seed; their interference with manipulated heads, indicated in the 

 tables, involves in some cases the question of the degree of fertility 

 shown by plants. As all manipulations were recorded in a day- 

 book, the final data for any plant were readily compiled from this 

 record, from the envelopes and from the tags of seed collections 

 into the final form of a card catalogue. 



