W. Bateson and a. E. Gaikdner 271 



Varieties with aborted anthers are familiar in a great number of 

 plants. Some, as for example that of the Sweet Pea, are quite sharply 

 defined, others, as for instance that studied by Miss Pellew in Gamjxi- 

 nula carpatica may exist in many inturgrading forms. As in the 

 Caryophyllaceae and Labiatae, such tlowers may coexist in various 

 grades on the same plant, and may even be associated with normal 

 hermaphrodite flowers. In these and other Natural Orders flowers with 

 aborted anthers are both by systematists and writers on genetics often 

 referred to as females, and the species possessing them are called gyno- 

 monoecious or gyno-dioecious as the case may be. It is not easy to 

 apply any definition which will distinguish flowers or plants with 

 aborted anthers from the normal female flowers of some dioecious 

 species (e.g. Lychnis), but to avoid raising this theoretical question we 

 propose to follow the usage of some American authors and call them 

 male-steriles. In these flaxes the sterility of the anthers is nearly but 

 not quite complete. No grades of plants were recognized beyond the 

 ordinary hermaphrodites and the male-steriles, but anthers of the steriles 

 occasionally reach a degree of development sufficiently complete to pro- 

 duce a little good pollen. Flowers with this low degree of male-fertility 

 may be found sporadically, as it seems, on any male-sterile plant. From 

 their pollen a few seeds have been obtained in self-fertilisation which 

 gave rise again to male-steriles only. No degree of male -sterility was 

 ever observed in the flowers of ordinary flaxes. In the breeding work 

 it was not thought necessary to emasculate the male-sterile flowers, and 

 in only one mating (Expt. 5) is there reason to suppose that disturbance 

 was caused by their pollen. 



In previous experiments on the genetics of male-sterility the male- 

 steriles were introduced as an already recognized type. In our work 

 they arose in F., from a cross between two fully hermaphrodite types. 

 Subsequent experience proved that the new form was brought in by the 

 pollen of the common flax, and that the procumbent is genetically 

 hermaphrodite on both male and female sides. Twenty-four fibre-flax 

 plants of various kinds (Expts. 6 — 10) tested by using their pollen on 

 male-steriles, gave in all 640 plants, all male steriles. To these 24 

 which gave a uniform result may be added the white plant, from the 

 male side of which the original ^2 family containing male-steriles was 

 derived, and a tall blue plant on similar grounds (Expts. 1 and 2). 



One tall plant (Expt. 11) used as male on a male-sterile gave a 

 hermaphrodite. If authentic, this constitutes a single exception to the 

 rule that the pollen of normal flaxes carries the male-sterile only. 



18—2 



