OTHER METHODS OF SEX-DETERMINATION 247 



quickly settle down, while the latter continue to swarm for 

 some time and surround the female individual (Fig. 137a). 

 One of the male swarm-spores fuses with the resting fe- 

 male swarm-spore. Hartmann isolated individual parent 

 plants and when the swarm-spores were set free, tested 

 these en masse against each other. A typical result is 

 given in Table 3 (to the left) where union is indicated by 



3<? 4^ 59 7$ 11^13$ l4y 



5<? 



m 



13? 

 14? 



51$ 32? S3<? 35<f 38^ 40<J 



51^ 



32$ 



53<? 



35<? 



58.? 



40.? 



Table 3. 



the + sign and failure to unite by the — sign. Each kind 

 is tested against each of the other kinds. In most cases 

 the swarm-spores from a given individual behave con- 

 stantly either as males or as females with the other types, 

 but in a few instances swarm-spores that acted as females 

 in some combinations acted as males in other combina- 

 tions. Thus No. 4 (see Table 3, to left) and No. 13 give 

 results inconsistent with their reaction in other combina- 

 tions. Another exception is found in the reactions between 

 No. 35 and No. 38 (see Table 3, to right), both of which 

 are designated as males from their other behavior, yet 

 react to each other as male and female. Hartmann speaks 

 of certain individuals as strong females and others as 

 weak females according to the number of ^'clusters" that 

 they give in different combinations, and concludes that 

 weak females may function as males when opposed to 



