TO THE KNOWLEDGE OF PLATYZOMA MICROPHYLLUM. 
163 
Out of 890 small sporangia examined, 739 liad each more than 29 spores. In these 
sporangia spores of intermediate size were rare, and the largest number of large 
spores in any one sporangium was 3. 124 sporangia had each from 27 to 29 spores ; 
23 had not less than 19 spores, and in only four instances did the spore-count fall 
below 16. In the small sporangia the number of intermediate spores was increased 
when the spore-output was small. The number of large spores in the small 
sporangia was invariably low. 
A similar analysis of the spore-numbers may be made for the large sporangia. 
A« is shown in the following table, the large majority of the spores in the large 
sporangia were of the large type : — ■ 
Total Number 
of Spores present in 
the Sporangium. 
Number 
of Small Spores 
present. 
Number of 
Intermediate Spores 
present. 
Number 
of Large Spores 
present. 
16 
0 
0 
16 
16 
0 
1 
15 
16 
1 
0 
15 
15 
0 
0 
15 
15 
1 
0 
14 
14 
0 
0 
14 
14 
1 
0 
13 
13 
0 
0 
13 
12 
0 
0 
12 
12 
0 
2 
10 
12 
1 
5 
6 
Out of 110 large sporangia examined, 73 had each more than 14 spores. In these 
sporangia spores of either intermediate or small size were uncommon. In the 
remaining 37 sporangia the number of small spores did not increase in proportion to 
the fall in the number of large spores. The number of intermediate spores was, 
however, increased. 
The examples given in the above tables are representative of the entire number 
of sporangia examined. The conclusion seems justifiable that the small and large 
sporangia are not chance developments in Platyzoma, but constitute well-defined 
generic features. The small spore is characteristic of the small sporangium ; the large 
spore is typical of the large sporangium. The intermediate spore is an accompaniment 
of reduced spore-output in both sporangial types. The small and large spores are 
the dominant types. The spore-output in the small sporangia is typically high, over 
80 per cent, of the small sporangia examined having spore-numbers between 29 and 
32. The spore-output in the large sporangia is typically low. It has never been 
seen to exceed 16, but in 70 per cent, of the large sporangia examined it did not 
fall below 14. These figures suggest that the spore-output per small sporangium is 
theoretically 32, while that of the large sporangium is 16. It will not be surprising 
if, when the sporangial development in this fern is known, it is found that the dis- 
