266 



RESEARCHES ON FUNGI 



Fungi in which, after treating of Sarcoscypha protracta, I said : "In 



most Discomycetes, e.g. Morchella 

 conica, Aleuria vesiculosa, Galactinia 

 badia, Lachnea scutellata, and Ascobolus 

 immersus, the asci are heliotropic, i.e. 

 their outer ends bend so that they 

 point toward the direction from which 

 the strongest light comes, and the 

 operculum is situated symmetrically 

 at the apex of each ascus. The result 

 of these arrangements is that, when 

 the asci explode, the spores are suc- 

 cessfully shot away from the fruit- 

 bodies into the outer air." 



In 1927, J. S. B. Elliott,i in a brief 

 paper on Aleuria repanda, described 

 the response of the apothecia to uni- 

 lateral light. Apothecia came up on 

 an old jute hearth-rug in a garden 

 tool-shed into which light penetrated 

 through a hole in the door. She 

 found that, in preparation for spore- 

 discharge, each apothecium undergoes 

 two successive adjustments: (1) a 

 coarse adjustment concerned with the 

 apothecium as a whole ; and (2) a 



to its long axis. The spores „ t , , i -ji. j.i, 



are stuck together to form fin^ adjustment concerned with the 

 a single projectile B, the individual asci. In the coarse adjust- 



spores shown in detail. 0,a "* 



single ascus of a Saccoboius ment, the stalk of each young apo- 

 thecium bends toward the source of 



Fig. 126.— Saccoboius. Helio- 

 tropism of the asci. A, an 

 ascus of a Saccoboius from 

 sheep dung ; it is straight, so 

 the direction of the incident 

 light may have been parallel 



heliotropically bent toward 

 the source of light. Amass 

 of jelly surrounds the eight 

 spores and attaches the 

 spore-mass to the apex of 

 the ascus. Drawn by W. 

 Zopf. From his Die Pilze 

 (1890, p. 205). Magnifica- 

 tion : A, 450 ; B, 900 ; C, 540. 



light and thus causes the mouth of 

 the cup to become directed toward 

 the source of light (Fig. 127) ; while, 

 in the fine adjustment which follows 



1 Jessie S. Bayliss Elliott, ''Aleuria repanda Pers.," Trans. Brit. Myc. Soc, 

 Vol. XII, June, 1927, pp. 166-169. 



