CHAPTER II.-—DIFFERENTIATION OF THE THALLUS.—MYCELIAL STRANDS, 23 
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’ 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 ı 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 11. 
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 II. 
The formation of strands reaches its highest development, as far as is at present 
known, in the mycelium of Agaricus melleus. An excellent description ofthe 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 

! See Fries, Icones sel. Hymenomycetum, I, t. 61. 
