INHIBITORY EFFECT, OF LIGHT 107 



and was lighted by daylight only from below. The lighting was 

 accompHshed by setting the crystallising dish on a glass plate 

 supported by an inverted iron tripod at a window and by then 

 reflecting Hght upwards by means of a mirror placed beneath. 



In the top-lighted Culture A, many tiny rudiments of fruit- 

 bodies in the form of small white specks about the size of a pin's 

 head arose on the lower darkened side of the dung and a smaller 

 number on the upper lighted side. However, the upper lighted 

 rudiments soon ceased to grow and underwent abortion, whilst of 

 the rudiments which had arisen in the lower darkened situations 

 a few developed vigorously into mature fruit-bodies (Fig. 59, B). 

 In the bottom-lighted Culture B, numerous rudiments of fruit- 

 bodies arose on the upper darkened side of the dung and a smaller 

 number on the lower lighted side. Here again the daylight showed 

 itself to be the chief controlling factor in the selection of the rudi- 

 ments, for the lower, well-lighted rudiments soon ceased their develop- 

 ment and became aborted, whilst of the upper darkened rudiments 

 a few eventually developed vigorously into mature fruit-bodies 

 and shed an abundance of spores (Fig. 60). In both the cultures, 

 as soon as the fruit-bodies had pushed upwards so as to touch the 

 covering plates, more room for their development was provided 

 by replacing the plates by bell-jars. In the Culture B, the stipes 

 which were attached to the top of the dung at their bases only were 

 so badly fixed in the substratum (Fig. 60, B) that it became necessary 

 to prop them up in order to prevent the fruit-bodies from toppling 

 over. 



Cultures C and D. Set up simultaneously. After the dung 

 had been inoculated with myceUum, the dish of C was placed in a 

 dark-chamber from which all light was excluded and the dish of 

 T> was subjected to the maximum amount of daylight. In the 

 Culture D, only three dung-balls were used and these were so placed 

 that they did not quite touch one another. The crystallising dish 

 which contained them, covered by its glass plate, was set on another 

 glass plate which rested on an inverted iron tripod as in Culture B. 

 The tripod, with the glass plate and dish above it, was then set 

 at a window in a position as well lighted as possible. The dung- 

 balls were lighted above, in front, and at the sides by direct 



