ii6 



RESEARCHES ON FUNGI 



the case upon the enlargement of 

 the pileus and the elongation of 

 the stipe-shaft. 



Under natural conditions, the 

 length of the sohd stipe-base 

 depends upon the depth within 

 the faecal substratum at which 

 the fruit-body rudiment has 

 arisen. If the rudiment requires 

 to push upwards for only 1 cm. to 

 come into the light, its base will 

 remain short and bulbous, 0-5-1 

 cm. long (Figs. 63, B and C, and 

 64, B). If, however, it has to push 

 up 4 cm. or any greater distance to 

 come into the light, its base wiU 

 be 3-4 cm. long. If it has to push 

 up a distance between 1 and 4 cm. 

 in order to reach the light, its 

 stipe-base will be of a length 

 intermediate between • 5 and 

 4 cm. , corresponding to the amount 

 of upward growth before the light 

 is reached (Fig. 65, A). The 

 general result of the morphogenic 

 action of light on a fruit-body, 

 therefore, is to regulate the length 

 of the soUd stipe-base in such a way 



Fig. 66. — Coprinus sterquilinus. Vertical 

 section through a mature fruit-body 

 (part shown in Fig. 65, B) which 

 developed in complete darkness. Cul- 

 ture medium, sterilised dung-balls. 

 The fruit-body happened to originate 

 on the bottom of a horse-dung ball. 

 Its solid stipe-base, in the absence of 

 light, has developed to the maximum 

 length ; the hollow stipe-shaft and the 

 pileus are normal. The gills have just 

 begun to discharge their spores. Re- 

 duced to two-thirds the natural size. 



