A cytological difference of great importance between the two generations can only be mentioned in passing.
It is by means of the cytological evidence, however, that this problem will finally be solved.
And since this rule has been found to hold good for all the archegoniate series and also for the flowering plants where, however, the gametophyte generation has become so extremely reduced as to be only with difficulty discerned, it is natural that when alternation of generation is stated to occur in any group of Thallophyta it should be required that the cytological evidence should support the view.
The genus Nemalion has been recently investigated by Wolfe with the object of examining the cytological evidence.
Latterly, however, as the result of the cytological investigations of Mottier and Lloyd Williams, great advance has been made in our knowledge of the conditions existing in Dictyota.