Mar. 8, 1924 
Nocturnal Production of Sclerospora 
779 
Table I. Measurements, and ratios of length to diameter of goo conidia ( zoosporangia ) 
of Sclerospora graminicola arranged in size and ratio classes 
Length. 
• _ 
Diameter. 
Ratio, length to diameter. 
Classes. 
Num¬ 
ber of 
conidia 
in 400. 
Classes. 
Num¬ 
ber of 
conidia 
in 400. 
Ratio classes. 
Num¬ 
ber of 
conidia 
in 400. 
M 
M 
II to 12. 9 
7 
9 to 10. 9 
I 
0. 95 to 1. 04 
I 
13 to 14. 9 
25 
II to 12. 9 
III 
1. 05 to I. 14 
3 1 
15 to 16. 9 
67 
13 to 14. 9 
162 
i. 15 to 1. 24 
75 
17 to 18. 9 
119 
15 to 16. 9 
92 
i. 25 to 1. 34 
“5 
19 to 20. 9 
89 
17 to 18. 9 
30 
1. 35 to I. 44 
92 
21 to 22. 9 
5 i 
19 to 20. 9 
4 
i. 45 to i. 54 
46 
23 to 24. 9 
22 
1. 55 to 1. 64 
25 
25 to 26. 9 
10 
i. 65 to i. 74 
9 
27 to 28. 9 
6 
i. 75 to I. 84 
6 
29 to 30. 9 
1 
3 1 to 32. 9 
1 
33 to 34. 9 
2 
From the measurements presented above in graphic and tabular form, 
it is obvious that, although conidia are encountered which measure from 
12 to 34 fx in length and io to 20/i in diameter, the greater proportion of 
them are between 16 and 22ju long by 12 to 16 jjl in diameter. These 
measurements present an interesting comparison to those previously 
recorded for S. graminicola. In Europe, Schroeter (23, p. 775) gave the 
size of the conidia as 20/* long by 15 to 18/1 wide, while Saccardo (79), 
apparently using scanty and immature material, first recorded 12 to 15/1 
by 10 to iiju, and later (20, p. 238) modified this to 12 to 20ju by 10 to 
18 ix to include Schroeter’s figures. Others, such as Malbranche and 
Letendre (74), Fischer (5, p. 437), and Berlese (7, v. 9, p . 70) followed these 
two without making original measurements themselves. In the United 
States, Saunders (27, p. 38) is apparently the only one to give original 
measurements, 18 to 20 ix by 13 to 15/x, the others, from Farlow (4) to 
Wilson (33), following Schroeter and Saccardo. In the Orient, Butler 
(2) gave 22 to 30 fx by 12 to i6ju and Kulkarni ( 12 ) 19 to 31/x by 16 to 21/x 
for S. graminicola in India; while Shirai (24) for Japan, gave 24 to 28.8/i by 
16.8 to 19.2 fi for the usual size, but made the startling statement that at 
times giant conidia, 38.5 to 57.6/z by 19.2 to 24 fi, occurred. Although no 
exact comparison can be made with inclusive, limiting, nonquantitative 
measurements such as these, there seems to be a fair agreement between 
the European and United States figures and those of the writer. The 
measurements from the Orient apparently show a consistently greater 
length; but whether this indicates different specialized races or merely 
greater luxuriance of growth under tropical conditions remains to be 
determined. The remarkable discrepancy in size and shape reported by 
Shirai arouses the suspicion that he was dealing with two species, and 
demands thorough corroboration before this larger size is included as a 
correct measurement for 5 . graminicola. 
In shape, the conidia vary considerably, ranging from subspherical 
through ovoid and obovoid to ellipsoid, lemon-shaped, and rounded- 
