30 



RESEARCHES OX FUNGI 



tubes, or spines in any fruit-body, be represented by the con- 

 traction Sp. Inc. 



Then Sp. Inc.= - • 



'■ A 



The value of the specific increase has been measured in a few instances. 



For species of Agaricine;e the number of gills was counted and 

 the gill-systems studied. The number of gills of each size was 

 determined. A few gills of each size were dissected off the fruit- 

 body, phxced on paper, and drawn. The paper drawings were then 

 cut out with scissors, and their area determined by weighing them 

 against squares of paper marked out in square millimetres. The 

 fact that each gill has two sides was taken into account. With the 

 data thus obtained the total area of the gills could be calculated. 

 The value of A was calculated from measurements of the diameters 

 of the pileus and of the stipe. 



Full-grown specimens yielded the following results : — 



Si)ecieis 



Russula citiina . 

 Amanita rubescens 



Armillaria niellca 

 Tricholoina p^rsoiiatum 

 Hypholoina sublatLTitivnn 

 Psalliota campestris . 



Diameter of 

 Pileus in 



^lilliiiietres. 



6.3 



oO 

 76 

 76 

 ]27 

 76 

 98 



As an illustration of the method of calculating specific increase, 

 details for the specimen of Tricholoina per sonattiin will be given. 



Diameter of pileus = 127 mm. 

 Diameter of stipe = 28 „ 



Hence, the area of the underside of tlic })ileus, with the gills 

 removed, exclusive of the part occu})iL'd by the stipe, =12072-8 

 -GIG mm.2, or A= 120-1 cm.^. 



Number of primary ijills = 101 



„ ,, secondary ,, = 101 



„ „ tertiary „ = 202 



„ „ quaternary ,, = 404 approximately. 



