338 
Bower examined some of Lyon's slides and published a short 
account of the embryology of the form. A detailed embryo- 
logical investigation of this form 
by Campbell is in press (11). 
The majority of the young 
plants proves to be still attached 
to the prothallus (Fig. 1); two 
were already free (Fig. 2). The 
size varied from 1|—20 mm. The 
developmental range was be- 
tween those in which the second 
root (and fourth leaf) were 
Fig 1. making their appearance. Fig. 2. 
Position of the Embryo in the Prothallus. 
The Suspensor. 
According to Lyon (24), the position of the embryo is deter- 
mined by the suspensor, which develops first and later gives 
rise to the embryo (See also Bower (3)). He gives a figure of 
the young sporophyte, in which the suspensor 1s immediately 
connected with the neck of the archegonium. The position of 
the suspensor, however, varies considerably in the plants in- 
vestigated, as Fig. 3 shows. 
In plant 4, which is represented by a transverse section, the 
position of the suspensor is almost as it is in Lyons micro- 
photograph. In plant 1—3 the position is much lower. In these 
