ipiS-] 



DEVELOPMENT OF AGARICUS RODMANI. 



317 



shown in the section represented in Fig. 3, from the right-hand area. 

 The dark area in Fig. 9 represents the mass of deeply stained hyphse 

 of the new growth zone. Because of the compactness of the tissue, 

 very Httle detail is shown. But along the middle portion of the 

 figure between the lighter, open mesh of the ground tissue below 

 and to the right, and the dark area of the hymenophore primordium 

 above and to the left, a number of hyph« in advance of the others 

 are shown extending into the loose mesh of the ground tissue. 

 These are nearly parallel and their extremities are more or less dis- 

 tant, because they are in advance of the greater number of new 

 branches present in the more deeply staining area. No annular gill 

 cavity is present at this time. 



Growth and Increase of the Hymenophore Primordium. — The 

 growth and further organization of the hymenophore primordium 

 is readily studied by the aid of similar serial sections of successively 

 older stages of the basidiocarps. Sections of such stages are repre- 



^ 3 



Diagram 3. Lateral view through young basidiocarp at a shghtly later 

 stage of development than in diagram i. Hy = hymenophore; A. C. = 

 annular cavity; V. P. =^ veil primordium. 



Diagram 4. Zenith view in young basidiocarp at same stage of 

 development. See text for details. 



sented in Figs. 5-8 and 10-16. Diagrams 3 and 4 indicate how the 

 sections were made. From the condition show in Figs. 3, 4 and 9, 

 there is a rapid increase in the number of hyphse in the zone of new 

 growth, extending in the same direction, i. e., downward and ob- 

 liquely outward. During the increase in number the hyphas become 

 more crowded, are straighter and lie more nearly parallel. The 



