50 DIVISION I.—GENERAL MORPHOLOGY. 
sporophores, as far as they have been observed’, always begin their development as 
comparatively large compact tufts of hyphae springing from the mycelium, and we 
may even venture to assume that the great majority of compound sporophores take 
their origin, as here described, from many hyphae. At the same time it must be 
acknowledged that it has been found possible to follow them back to their very first 
beginning with perfect certainty only in the few cases which have been noticed 
above. 
Many inconspicuous compound sporophores, such as the gonidiophores of Uredi- 
neae and the stromata of many small Pyrenomycetes, remain as it were in the stage 
of the tufts of hyphae and pass into their ultimate form without further remarkable phe- 
nomena ofgrowth. But where a larger structure is produced, the course of development, 
amid great variety of detail, discloses two chief types, which closely resemble the two 
types of growth above described, for the mycelial strands on the one hand and for the 
sclerotia on the other. In the one type, asin the formation of sclerotia, the growth 
is nearly uniform for a long time in all parts of the structure; then comes the second 
chief stage, the ultimate development by internal differentiation. The compound 
sporophores of the Gastromycetes show this mode of proceeding in the most marked 
manner. In the other type the general course is progressive, just as it is in the 
mycelial strands or in the single hyphae, advancing in the direction of fixed spots in 
the surface, which are themselves pioneers in the advancing growth and maintain it by 
formation of new cells; as any section becomes removed from these spots growth in 
it ceases, and its component elements assume their definitive character. According 
to the form of the whole structure and of the superficial portion ofit in which 
progressive growth occurs, this growth may be said to advance towards the apex, to 
be apical (acropetal), or to be marginal, and the peripheral progressively growing 
spots by another usage may be termed growing points or margins ; or growth is 
progressive towards the whole of the free surface of the structure which bears the 
hymenium, as in the horse-shoe-shaped pilei of Polypori which are several 
years old, and in other Hymenomycetes also with various modifications and 
limitations. 
Growth thus on the whole progressive does not preclude intercalary areas of new 
formation and extension from making their appearance between portions in which 
these processes had ceased; but the actual occurrence of these areas has never been 
distinctly proved in any of the cases which belong strictly to this type. 
On the other hand, the combination of the two types of growth has been 
ascertained in a considerable number of species. We find, for instance, internal 
differentiation and subsequent progressive growth in the compound sporophore which 
is the chief product of Amanita. The young stipe of the Coprineae® has a transverse 
intercalary zone in the part just below the apex, in which there is continued formation 
of new cells by (meristematic) division ; the velum also has intercalary growth, but 
all the growth of the pileus and the final elongation of the stipe is progressive. In 
the Xylarieae, Cordyceps, &c. the growth of the club-shaped sporophore is progressive 

1 Hartig, Zersetzungserscheinungen d. Holzes, p. 21 (Polyporus annosus), p. 32 (Trametes Pini), 
p. 41 (Polyporus fulvus), p. 50 (P. mollis), p. 98 (Hydnum diversidens), &c. 
2 Goebel in Arbeiten d. Bot. Instit. zu Würzburg, II, 354. 
® Brefeld, Schimmelpilze, IIT. 
