TREE, - CN MP و می‎ OMA. S n 
4 ہس 
سی تحت سیورس نم Ea‏ 
SPORE DISSEMINATION 29 
which spores are found by microscopic examination after the lapse 
of a few hours, from the substratum, indicates the distance to 
which the spores are discharged. Of course the experiment must 
be repeated a great many times and the distance of the surface 
which collects the spores must be varied in such a way as to locate 
the extreme distance to which spores are ejected. This has been 
done a great many times with P. curvula. In the majority of 
cases the substratum with the growing plant was placed in a fruit 
jar and ordinary white paper was supported at proper distances 
to collect the spores. In six experiments the distance varied be- 
tween 5 and 9 cm. ; the greatest distance being obtained in the 
last trials. It is quite probable that the later observations are the 
most accurate for it was discovered after two or three trials had 
been made, that the apparent distance to which the spores are 
thrown upward depends upon the conditions of the growth of the 
plants. As has been observed a great many times by others, 
Zopf especially,* these fungi are strongly heliotropic, curving in a 
short time under unequal illumination in such a way as to turn 
the ostiolum toward the source of light. Plants grown under 
these abnormal conditions are evidently unsuited for the determi- 
nation of distances to which spores are ejected, because they will 
not be thrown directly upward when the perithecia are curved. 
Indeed if the beak is much curved, as often happens in other 
species of this genus, normal action is interfered with to such an 
extent that the spores are simply pushed out of the ostiolum in 
such a way as to form a globular mass resting on and remaining 
attached to it. This condition was once produced in a very strik- 
ing way in P. curvicolla, The plants were grown in a large 
Petri-dish, and the substratum was surrounded by paper in such a 
way as to admit light diagonally from above. After the first four 
days the position of the paper was changed in such a way as to 
change the direction of the light, with the result shown in PY. z. 
f. 6. A great many perithecia were found which had globular 
masses of spores on their apices. This condition, however, is 
usually more or less prevalent in any culture on account of the 
irregularity of the substratum which in itself causes more or less 
of an unequal illumination in cultures made within doors. 
* Lor. cit. 
