CHAP. II.—-DIFFERENTIATION OF THALLUS.—COMPOUND SPOROPHORES. 51 
(acropetal), and the perithecia are subsequently formed in them by internal differentia- 
tion ; other instances might be given. 
Some compound sporophores with acropetal growth are normally and often 
uniformly branched, as in many Clavarieae, the Xylarieae, and Thamnomyces. The 
ramifications appear always to arise as bifurcations of the growing points, but this has 
not yet been sufficiently investigated. Inquiry is also needed in the cases of 
supposed monopodial and always slightly irregular branching seen in Agaricus 
racemosus, Isaria brachiata, and some others. Peziza Sclerotiorum often has 
irregulary disposed exogenous branches on the stalk-like portion of a compound 
sporophore, especially on the part near the ground. We are not concerned here with 
branching which is purely adventitious, artificially excited, or monstrous. 
The duration of growth under normal and favourable conditions differs much in 
different species. In the small delicate fleshy Coprini the whole process, from the 
commencement to full ripeness and decay, may be completed, according to Brefeld, in 
8-10 days, while the solid woody Polyporeae maintain a progressive growth for 
years; Trametes Pini, for example, according to Hartig for 50-60 years. There 
are all possible intermediate cases between the two extremes. Long-lived species 
necessarily advance and remain stationary periodically with the change of the seasons. 
Apart from this latter influence, the course of growth under uniformly favourable 
conditions is marked by the same order in the Fungi as in the higher plants. First 
there is the laying down of new parts by formation through division of meristem of new 
tissue-elements accompanied by a small increase in volume; then the differentiation of 
the tissues takes place, and lastly the final elongation and increase of volume. The first 
two operations are performed slowly and steadily at least relatively to the third, the 
one passes gradually into the other; and the transition to the third stage is also 
gradual in the forms which are not fleshy, such as the Xylarieae and the leathery and 
woody Hymenomycetes. But in the forms with fleshy succulent substance, especially 
the Hymenomycetes and Phalloideae, the transition to the third stage is often abrupt, 
and this stage itself is traversed with relative and absolute rapidity. Of the 8-ı0 days 
occupied by the growth of the small Coprineae mentioned above the last tenth at 
most was devoted to the final elongation and expansion, the former stages requiring 
7-9 of the 8-10 days. In the case of many other fleshy Hymenomycetes, such as 
Amanita, the time necessary for the first two stages is much longer than this, and 
Schäffer is not much beyond the mark in estimating it at a year in Phallus impudicus *; 
but more exact determinations are desirable. But the final elongation and expansion 
are accomplished in all these cases, under favourable circumstances, in a few days at 
most. The proverbial rapidity with which the succulent Fungi shoot up from the 
ground, as is the case with the green vegetation in spring, is chiefly due to 
the abruptness of the final extension of the structure which has long been in existence 
and slowly and gradually developed. 
It has in no case been shown with perfect certainty that the peripheral 
extremities of the hyphae, which take the lead in progressive growth, remain the 
same during the whole process, and that the compound sporophore therefore is built 
up-of the united branches of a constant number of monopodially branched primary 

1 Der Gichtschwamm mit dem griinschleimigen Hute, Regensburg, 1760, p. 7. 
E 2 
