M. [>,. Crane 



Sterilitv ok Antheus. 



The Htamcns of tlio tomato arc syngcncsious, and form a cone round 

 the stigma. ITsually the surface of the stigma is slightly below the 

 apex of tile fdiir, and cjuse U> the poies in thi' anthers from which the 

 pollen dehisces. The tomato is therefore well adapted for self-pollina- 

 tion, and when the Howers aix; in a receptive condition any mechanical 

 movement of the pl.inl further assists in I he dispei'sion of the iJollen ; 

 the stigmatic surface being also partially protected by the; stamens, the 

 chances of cross-pollination occurring are few. Insects of any kind 

 rarely visit the flowers. Those which do are mostly small, and they 

 usually confine themselves to the base of the flower. With close 

 observation I hav(^ not on a!iy occasion seen insects near the surface 

 of the stigma. 



In 1913 my attention was attracted to two individuals in the Fo 

 family growing in the open which fiiiled to set fruit. Ujjon examining 

 their fluwi'rs I found the stamens were reflexed and somewhat aborted, 

 and that the stigmas were exposed and protruded about an eighth of 

 an inch beyond them. At first I concluded that it was due to this 

 structural ditierence that no fruit developed, as I assumed that this 

 would prevent self-pollination. Some time afterwards many of the 

 anthers were examined and found to be contabescent and devoid of 

 pollen. (Plate VI, fig. 14.) 



Later these plants produced many parthenocarpic fruits, doubtless 

 without any sexual process. Upon examining a considerable number 

 of these fruits only two were found which contained any seed: one had 

 two, the other only one. These were probably due to cross-pollinatiim ; 

 the protruding stigma would be favourable to it occurring should pollen 

 be conveyed by wind from neighbouring plants. 



The flowers on an inflorescence of one of these plants were isolated 

 and crossed with the original ? parent; the resultant fruits were full 

 of seed and much larger than those without seed. The following year 

 twenty plants were raised from the above cross, and they were all 

 hermaphiodite; the stamens were normal, and they produced fruit 

 freely. 



In potatoes Salaman(3) found that the sterility of the anthers 

 behaved as a dominant. He refers also to Darwin's (1) observations 

 on sterility of anthers, which condition when the anthers were aborted 

 he called " contabescence," following (Jiirtner. 



