142 
M40 are 57.8 and 64.6 » respectively, far below the mode of the original, 
which was 81.6 u. M36 shows less striking difference, but this is still 
marked. Comparison of the means shows those of M36 and M40 to be 
approximately 17 and 18 divisions (1 division=3.4 u), while the original 
was 23 divisions. In other words, the conidia of M36 were only about 
three fourths the length of the normal conidium of H. No. 1. Such dif- 
ferences as they appeared in the microscope are shown in I'l. XXVI. The 
difference in variability is also strikingly large. 
Striking variation in conidial breadth, both relative and absolute, was 
observed. Graphs and data of the more pronounced cases are presented 
in Fig. Q and others are given later. In connection with Fig. Y (Graphs 
114-138) are given summary data on the conidial length of saltants in- 
cluded in this study. It is to be noted (Graph 6A, Fig. B) that whereas 
the mode of the ordinary conidium stood at 20.4 w and no conidia exceeded 
a thickness of 23.8 uw, the modal thickness of M8-7 (Graph 75, Fig. Q) is 
23.8 w, with many conidia 27.2 win thickness, one even 30.6 uw. Such dif- 
ferences between saltants and the parental form are presented to the eye 
in Pl. XXVI. 
The ratio of conidial length to conidial breadth is perhaps still more 
striking than the mere variation in length. In such variants as M6 (PI. 
XXVI, >) and M8, while increased greatly in thickness the conidia were 
at the same time absolutely shorter, thus emphasizing to the eye both 
differences. The ratio of length to breadth in H. No. 1 is as follows: 
mean length 22.62 = .05 
mean breadth —-6.03 + .04 
= Hees se 
while in a sample of one of its saltants this ratio is 
mean length 20.67 += .22 
= — = 2.64 + .04* 
mean breadth Hasyeess sili 
and in another sample of the same saltant it is 
mean length 19.58 + .30 a ae 
- = = - = Dior SS Ae 
mean breadth 7.30 += .06 
a \2 
(Vy) 
=+ pe EL 
ie A 
*Probable error was computed according to the above formula kindly furnished me by Dr. J. A. Det- 
lefsen, where a = probable error of A; b =probable error of B; and E =probable error of me 
