1913] MATHENY—BROWN-ROT FUNGUS 425 
Before attempting to give the size of the conidia of the American 
brown-rot fungus, it was considered necessary to make a series of 
comprehensive measurements of the spores taken from fruit from 
different parts of the country. Such measurements were made. 
The method of this work was that of the ordinary laboratory pro- 
cedure. An ocular micrometer having a scale value of 3.6 u was 
used. Unconscious selection was avoided by measuring all the 
spores that arranged themselves in bunches on the slide, or always 
measuring the one nearest the right side of the eyepiece scale. 
Care was taken to allow the spores to become fully turgid in the 
water before the measurements were started. 
The results obtained in these measurements are of considerable 
interest from another point of view. WoRoNIN and Pottocx (20) 
have suggested that these conidia vary in size to a considerable 
degree according to the host or culture. Others suggest that light 
and darkness also cause a variation in size. In none of these 
instances, however, is the method of measurement mentioned or 
the number of conidia measured. In the results obtained in this 
study no such variation was ever in evidence. On the other hand, 
when all the measurements were done and the figures computed 
for a mean, variation in size of conidia was found to be practically 
nothing. 
SPORE MEASUREMENTS 
(In each case the upper row of figures represent microns, and the lower row the 
number of spores of that size.) 
SPORES FROM MUMMIED PLUMS SENT BY J. W. Apams, FRANKLIN, IND. 























No. 
. ean 
‘ smanetaed Length 
Fr. s 2-1 23 13.7 | 14.4 | 15.1 | 15.8| 16.6] 17.2] 18 | 14.48 
3 13 ° 6 I 2 
745 Width 
7-377 8.6] 9.4 10,8.4-£1.5 pace ages, Bate 9.42 
4 23 31 47 II ee A 






