I9IS-] DEVELOPMENT OF AGARICUS RODMANI. 33 5 



tain individuals. A protoblem" is very likely present, but it is diffi- 

 cult to distinguish in primordia havng a subterranean origin because 

 of the ease with which the delicate protoblem is removed while re- 

 moving the soil, and especially in the forms and species of Agaricus 

 with a white pileus. In those with a brown pileus, like Agaricus 

 campestris var. bohemia of the commercial spawn growers, the 

 delicate, white protoblem is very distinct. 



Differentiation of an Internal Annular Hymenophore Primor- 

 diimi. — The first evidence of internal differentiation is the appear- 

 ance of an internal annular zone of new growth in the region of the 

 smaller end of the oval fruit body. This can be studied with ad- 

 vantage by means of serial, longitudinal sections. A median longi- 

 tudinal section is shown in Fig. 3, while a " tangential " section, i. e., 

 parallel with the axis of the basidiocarp, but through one side of the 

 annular zone of new growth is shown in Fig. 4. Diagrams i 

 and 2 (in the text) show how the sections were made. Fig. 3 is 

 from the region marked by the line 2, while Fig. 4 is from that 

 marked by the lines i and 3. The darker staining areas in Figs. 3 and 

 4 mark the position of the zone of new growth. In the median 



11 The delicate, floccose, primary universal veil, or protoblem was ob- 

 served by Fries on Agaricus campestris and a few other species, and 

 called by him a subuniversal veil. Vittadini (in Fung. Mang., 147, pi. 18, 

 fig. 2, 1835) describes and figures it in connection with his study of the 

 development of his Agaricus exquisitus. But in this species he seems to con- 

 fuse this delicate universal veil (protoblem) with what he terms the volva 

 in several species of Agaricus. He also applies the term volva to the 

 lower limb of the annulus in Agaricus exquisitus and in Agaricus edulis. 

 He says (/. c, 148) this delicate universal veil in A. exquisitus is per- 

 fectly similar to that which constitutes the veil of the " Tignose," i. e., the 

 scaly Amanitas like A. muscaria, etc. Vittadini also states (/. c. 147) 

 that Trattinnick observed this delicate universal veil (protoblem) on 

 Agaricus edulis (the species which Trattinnick describes as A. edulis is 

 different from A. campestris edulis Vitt. or A. rodmani Pk.), but it appears 

 that Vittadini misinterpreted Trattinnick's statment. The latter says, in order 

 to prevent confusion one should avoid (/. c, p. 73) taking for the edible one 

 a mushroom (74), which may have also only the slightest trace of a mem- 

 brane which in youth envelopes the entire mushroom, including pileus and 

 stem, down to the roots. " Um Verwechslungen zu vermeiden, hiite man 

 sich statt der Gugemuke einen Schwamm zu nehmen " (73), "(d) der auch 

 nur die geringste Spur von einer Wulsthaut haben sollte, die in der Jugend 

 den ganzen Schwamm mit sammt den Strunk und Hut bis auf die Wurzel 

 verhiillet " (74 Die essbare Schwamme, 1830). 



