252 BOTANICAL GAZETTE [oCTOBER 
is necessarily to be found in other plants until they have been studied, 
though it is probable that it is true for at least some of the other 
species of Agaricus (Psalliota). FAavop found that usually the pri- 
mordium of the pileus was organized in the apex of the homogeneous 
young carpophore before the appearance of the primordium of the 
hymenium, and this seems to be true in certain species of Hypholoma 
studied by one of my students. In fact Fayop asserts that this can 
be accepted as a general law. The primordium of the pileus is the 
first to appear in the organization of the parts of the carpophore 
from its primordium. It is shown by the area of hyphae composing 
it taking on a deeper stain in sections. It is in the form of an inverted 
bow] convex above, concave below, and Agaricus rubellus (Psalliota 
rubella) is one of the forms which he studied. The only exceptions 
which he admits are the coriaceous forms like Lentinus (I. ¢., p. 296): 
In this respect these cultivated forms of Agaricus campestris show 
also an exception to this rule, and the primordium of the pileus is to 
be regarded as diffuse in the primordium of the carpophore, as he 
suggests for the coriaceous forms. 
The question of the simultaneous organization of the pileus an A 
stipe from a young homogeneous fruit body is an interesting one in 
view of the different theories held by some of the earlier students. 
Thus Fries”? said: “Omnia organa simul, nulla subevolutione nova 
successive explicantur. Ommes extremitates ipsius Fungi explicatt 
jam in aetate juvenili adsunt,” 7. e., ‘all organs are unfolded simul- 
taneously, none by new successive development. All parts (or 
extremities) of the unfolded fungus itself are already present the 
young stage.” He thus believed that in the very young fruit body 
the organs or parts, though rudimentary and invisible, were all present, 
their manifestation and expression was a matter of unfolding. 
This interesting conception is shown also in another place (I. ¢ 40), 
where he expresses his view of the general mode of growth oe 
fungi as compared with that of the algae as follows: “Fung! 1? geal: 
plerumque directiones a centro, quod junius, sese expandunt, : 
“Fungi, though young, expand from the center in almost all ee 
tions.” All the parts being present, the growth in the center P™ 
them outward, as they enlarged, into their respective positions, W 
20 E. Fries, Systema orbis vegetabilis, part 1, 40, 43- 
