340 



Conjugate 



but in the present state of our knowledge they may for the time being be 

 regarded as aplanospores. 



Fig. 212. Tcmnogametum heterosporum W. & G. S. West. A shows completed scalaviform and 

 lateral conjugation in the same filaments ; B, zygospore formed by scalariform conjugation ; 

 C and D show early stages in the fusion of the gametangia; E is an abnormal case in which 

 two adjacent gametangia were cut off in one filament, one of them having conjugated in a 

 scalariform manner; F, early stage in lateral conjugation; G, completed zygospore. ch, 

 chloroplast ; g, gametangium ; py, pj'renoid; vg, vegetative cell; zl, zygospore produced 

 by lateral conjugation; zs, zygospore produced by scalariform conjugation. All x455. 



On the whole it seems highly probable that Gonatonema is specialized and 



