ON THE DEVELOPMENT OF LICHENOPORA VERRUCARIA. 117 
*50 to ‘70 mm. in length, and from ‘35 to ‘55 mm. in breadth, 
although these limits may be passed in either direction. The 
average of eight cases in which I was able to estimate the 
length of the colony (in sections) was ‘53 mm., and the average 
breadth (twenty-two cases) was ‘44mm. The entire colony 
(fig. 4) might well have been in this stage, although still 
older colonies are commonly in Stage D, as may be shown by 
counting in the sections the number of their fully formed 
zocecia. 
The distinction between Stages C and D is obvious enough 
as regards the embryo and its connected structures. But the 
change from one stage to the other implies no more than the 
degeneration of a polypide and its alteration into the condition 
of a brown body. We should not, therefore, expect to be able 
to distinguish by external features alone between colonies in 
the two stages. This is all the more difficult, since the period 
in the growth of a colony which corresponds with a particular 
stage in the embryonic development varies within wide limits. 
Stage E.—Disappearance of the Suspensor and Enlarge- 
ment of the Embryo. 
This stage immediately precedes the beginning of embryonic 
fission. Fig. 29 represents an embryo found in a colony mea- 
suring ‘56 mm. in breadth. The fertile zocecium was almost 
certainly z?. The embryo has unmistakably increased in size 
compared with the embryos in the previous stage. While that 
of fig. 27 measures 28 in greatest length, that of fig. 29 
measures 70 y, which is exactly two and a half times as much. 
Other changes have also taken place. The suspensor has 
ceased to be a definite structure, and the embryo has moved 
towards the brown body, so as to take the place originally 
occupied by the suspensor. The follicle is still distinct in this 
series of sections, but the section figured only cuts its edge. 
The first indication of the commencement of this stage is given 
by the longitudinal elongation of the embryo, which then 
begins to extend beyond the original limits of the follicle into 
the stalk connecting the latter with the brown bedy. We 
