100 SIDNEY F. HARMER. 
During my study of the development of L. verrucaria, I 
have been much struck with the frequency with which the 
zocecia z” and z® form the starting point of the. ovicell. This 
result was first obtained by a study of sections; but, as has 
already been pointed out, it was afterwards amply verified by 
an investigation of the entire colonies. Some statistics will 
bring out the striking nature of this phenomenon. In 108 
colonies belonging to Stages B to G, or being fertile colonies 
in which degeneration of the embryo was taking place, I have 
been able to determine the fertile zocecium. In the cases of 
the older colonies (Stages E to G), it is easier to recognise the 
fertile zocecium when it happens to be z? or z? than when it is 
a younger zocecium ; and the older stages have consequently 
been omitted in the second column of the table. 
Table showing the Frequency of the Occurrence of 
z* or z° as the Fertile Zowcium. 
Stages B—G 
and degenerating Stages B—D. 
fertile colonies. 
No. of cases in which z? is fertile ‘ ‘ 44 j 99 
2 rs Z . ‘ - Si ‘ 15 
29 y) 2° or 23 ee) . . 8 ° 5 
55 R 5 Pizaee : : 15 ; 1 
“4 3 Piz us : ; 8 : 6 
re a a younger zocecium is 
fertile . : 3 6 ‘ 5 
- s two zoccia are fertile . 6 : 3 
“A a the fertile zocecium could 
be determined . 5 108 ‘ 75 
Total number of colonies investigated . : 175 : 95 
As it is by no means easy to determine the fertile zocecium 
in unfavorably orientated sections, there is obviously room 
for error in the above results; but as I have only entered 
cases in which I have felt confident that I could really deter- 
mine which zoccium was fertile, I believe that the table is 
substantially accurate. In estimating the bearing of these 
numbers it must be noticed that in a considerable proportion 
of the cases in which the fertile zocecium is entered as ?2? or 
