188 TKANSACTIO^'S AND PKOCEEDINGS OF THE [Sess. Lxiii. 



There was no uniformity on this point in my specimens, 

 sometimes the one, sometimes the other was the larger 

 cell, occasionally the male was the shorter and thicker 

 tube, at other times, when failure of conjugation occurred, 

 the female tube was abnormally long and slender, although 

 never attaining the dimensions of a rhizoid, as described by 

 West. When three cells conjugated, sometimes the female 

 sent out two tubes to meet the corresponding ones of the 

 two males, at other times one broad tube faceted for the 

 males, the facets sometimes carried to extreme, so as to 

 appear an incipient hrancliiwj. 



Again as to the orientation of the conjugating tubes : 

 when a cell sent out two tubes, these might be on opposite 

 sides of the cell, and practically in the same plane, or they 

 might be in any plane at any angle to the first one. 



The variation affected the size of the zygospore ; in the 

 same filament there were considerable differences in this 

 respect. See Figs. 26 and 27. 



Formation of the zygospore in the conjugating tube is 

 said never to occur in nature. In several specimens of 

 interrupted scalariform conjugation, an interesting inter- 

 mediate condition occurs. The zygospore is dumb-bell 

 shaped, and stretches through from cell to cell. That this 

 is not a protoplast in passage, but an actual zygospore, is 

 shown by the rounded-off appearance of the mass, and by 

 the presence of the characteristic membranes. In other 

 cases, where azygospores were found, one of these, the 

 smaller, was partly in the coujugating tube. 



Considering first the cases wliere conjugation takes 

 place between two cells — 



Fig. 1 shows the normal scalariform mode. In Figs. 

 2 and 3 is seen an interesting case where, after normal 

 conjugation, the female cell contains two zygospores of 

 nearly equal size in the former, of very unequal size in 

 the latter. Figs. 4 and 5 show azygospores. A small 

 part or none of the protoplasm has passed over, and the 

 two protoplasts have rounded off, encysted, and become 

 spores. In Fig. 6 a similar condition is seen, with the 

 additional interest that the smaller of the two spores, the 

 male, is partly in the conjugation tube. This forms a 

 transition to the following. Fig. 7 depicts a condition 



