3 2o RESEARCHES ON FUNGI 



that reducing sugars were present. One of these sugars was 



maltose. 



Glycogen exerts almost no osmotic pressure, whilst maltose and 

 allied sugars exert a high osmotic pressure. There is therefore every 

 reason to suppose that, in the palisade cells, whilst glycogen is 

 being transformed into sugar, the osmotic pressure of the cell-sap 

 is gradually increased by several atmospheres ; and we may con- 

 clude that it is the increase in the osmotic pressure of the cell-sap 

 of the palisade cells which is chiefly responsible for the discharge of 

 the Sphaerobolus gun. 



Since the fruit-bodies of Sphaerobolus normally open and dis- 

 charge their projectiles in the morning and since darkness delays 

 opening and enfeebles discharge, it seems probable that the light 

 and heat of the fore-noon hours have an important influence on the 

 transformation of the glycogen into sugar. In all probability, also, 

 the transformation of glycogen into sugar is aided by an enzyme 

 — glycogenase — but this has not yet been proved. 



" Le glycogene," said Errera, 1 " est l'amidon des Champignons," 

 and he regarded it as the reserve carbohydrate of fungi. Since, as 

 Miss Walker and Miss Andersen 2 point out, it occurs in the palisade 

 layer of Sphaerobolus before expansion takes place, in the stipes of 

 Coprini before their elongation, in the asci of the Discomycetes 

 before they become stretched and (I may add) in the unexpanded 

 stipe of Phallus impudicus, and since it disappears and is replaced 

 by sugar in all these organs as they expand, we may conclude with 

 Miss Walker and Miss Andersen that one use of glycogen in fungi is 

 to provide a substance which can readily be transformed into one 

 or more soluble substances of high osmotic value. 



When a fruit-body opens stellately, the inner surface of the 

 palisade layer, which becomes exposed to view above the projectile, 

 is bright orange-yellow. Apparently, the orange-yellow pigment, 

 which resides within the cells of the palisade layer, has not been 

 investigated ; but it probably resembles that of Pilobolus, the 

 Uredineae, Dacryomyces deliquescens, Peziza aurantia, etc., in 



1 L. Errera, " Sur le glycogene chez les Basidiomycetes," Bull, de VAcad. roy. 

 de Belgique, 3 ser., T. VIII, 1884, and Mem., T. XXXVII, 1885. 



2 L. B. Walker and E. N. Andersen, loc. cit., pp. 157-159. 



