CHAPTER II. — DIFFERENTIATION OF THE THALLUS. — MYCELIAL STRANDS. 2$ 



hyphae with transverse septation, which vary according to the species. They generally 

 run parallel to the longitudinal axis of the strands and are straight or undulating, and 

 are either grown together by their lateral walls, as in Polystigma stellare, Agaricus 

 Rotula and A. metatus, &c, or they are loosely woven together, as in Elaphomyces, 

 the Nidularieae, Scleroderma, and the Hymenogastreae. 



The structure of such Phalloideae as have been examined, of the Lycoperdaceae 

 and of some Agarici, is somewhat more complicated. The strands of Phallus 

 impudicus creep in the ground and may be several feet in length and 2 mm. in 

 thickness. A transverse section through the stronger branches shows a thin, firm, 

 white, outer layer or rind enclosing a thick cylinder of a brownish colour and 

 gelatinous appearance (the medulla). The central and larger portion of the 

 medullary substance consists of a felt of tough gelatinous character, in which the 

 hyphae run longitudinally and are slightly sinuous and of unequal thickness. The 

 outer portion of the medullary substance is exclusively formed of thicker hyphae. 

 The rind is composed of a few layers of broad thin-walled hyphae wound firmly round 

 the medullary cylinder in narrow spiral coils. It is easy to see that these hyphae 

 spring as branches from the peripheral elements of the medullary tissue, then curve 

 outwards and join the tissue of the rind. They form on their surface short distant 

 branchlets which make the strands appear as if clothed with short hairs. The entire 

 surface of the strands is covered with calcium-oxalate. 



The strands of Agaricus platyphyllus 1 are very like the above in thickness, 

 appearance, and structure, only the hyphae all run in the longitudinal direction and 

 their walls are on the whole of firmer texture. 



The strands of Phallus caninus resemble likewise those of Ph. impudicus, but 

 are smaller in every respect. Here too all the hyphae run parallel to one another in the 

 stouter parts which may be 1 mm. in thickness, and the white rind is distinguished 

 from the yellowish gelatinous medullary substance which contains no air by more 

 loosely interwoven hyphae, by air-filled interstices, and by the copious deposit of 

 calcium-oxalate on the hyphae and in the vesicular cells described on page ir. 

 Clathrus shows similar characters as far as my observation has gone. The rind and 

 the medulla are often less distinctly separated from one another in the more slender 

 branches of higher orders, but the former is always distinguished by its covering of 

 calcium-oxalate. The strands of the Agarici (Agaricus campestris, A. aeruginosus, 

 and A. praecox) and those of the Lycoperdaceae have the appearance of the 

 slenderer branches of Phallus caninus and the same structure in all important points. 

 The presence of the calcium-oxalate varies according to the genera and species, as 

 was stated on page 1 1 . 



The formation of strands reaches its highest development, as far as is at present 

 known, in the mycelium of Agaricus melleus. An excellent description of the structure 

 and growth of this plant by Jos. Schmitz was published, with some additions by 

 myself, in the first edition of this work ; its life-history was elucidated by R. Hartig, 

 and our knowledge of it was subsequently completed by Brefeld's cultures. There is 

 the more reason for giving an account of the results of these investigations in this 

 place because Agaricus melleus is the only one of the forms which we are at present 

 considering in which the course of development has been followed from beginning to 



1 See Fries, Icone's sel. Hymenomycetum. I, t. 61. 



