Mar. 1899.] BOTANICAL SOCIETY OF EDINBURGH 187 



filament. A loop tube is formed at contiguous ends of 

 neighbouring cells, and through this one protoplast moves 

 into the adjacent cell. This, as a rule, occurs in groups of 

 four cells — the zygospores being formed in the central two 

 cells, while the outer cells are empty. 



Curiously enough, neither cross nor lateral conjugation 

 occurred in the artificial cultures, although both might 

 have been expected to be of common occurrence. The 

 modifications were all variations of the normal scalariform ; 

 false cross conjugations were frequent, and interrupted con- 

 jugations very abundant. 



A zygospore may be the result of thg conjugation of two 

 protoplasts, male and female ; or of three, two males and 

 one female. Further, female filaments are described as 

 being very much the more abundant, so that conjugation 

 between one male and several female filaments is very 

 common. West confirms this by figures. 



The converse was found to be the rule in my artificial 

 cultures ; females were very much in the minority, and 

 bundles of male filaments from three or more were found 

 around one female, conjugating at intervals along their 

 length. Starvation tended, apparently, to increase the 

 number of males. Such cases as in Figs. 21 and 25 were 

 found in every mount, while the equality, as seen in 

 Fig. 24, was very uncommon. The preponderance of 

 males was seen even in the conjugation between two 

 filaments, where two male cells conjugating with one 

 female were found, as well as extremely numerous cases 

 of such conjugation interrupted. 



None but imperfect conjugations of two females and one 

 male occurred, and that rarely. 



Again, Bennett (" On Eeproduction in the Zygnemaceie," 

 "Jour. Lin. Soc," 1884, vol. xx. p. 430) states that it is 

 possible, before conjugation has actually occurred, to dis- 

 tinguish the female from the male filament, by the larger 

 size of the former, and by the female part of the conjugat- 

 ing tube being shorter and wider. This was combated by 

 Bates ("On SexualitJ^of the Zygnemaceoe," "Jour. Quekett 

 Micros. Club," 1885, sec. ii. vol. ii. p. 104). West also 

 regards Bennett's distinction as of little value, and confirms 

 Bates'. 



