212 



DIVISION II. COURSE OF DEVELOPMENT OF FUNGI. 



Pyrenomycetes protuberant below and with a short neck ; they are sunk in the thallus 

 but have the free extremity of the neck on a level with the outer surface. The neck 

 is traversed throughout its length by a canal open at both ends, the canal of egress. 

 The wall of the inner ventral portion, which is formed of a close weft of hyphae, bears 

 a hymenium on its inner surface composed of delicate hyphal branches of uniform 

 height closely packed together, and converging in the direction of a central space 

 which is free from them and is in open communication with the neck-canal. These 

 hyphal branches behave like basidia or sterigmata, and abjoint serially a'nd successively 

 numerous spermatia at their apices in the form of small cylindrical rod-like cells. 

 The apparently homogeneous protoplasm of the spermatia has a sharply defined 

 contour, outside of which is a hyaline jelly, which swells and deliquesces in water and 

 forms probably the outer layers of their membrane. In this gelatinous envelope the 

 spermatia when abscised lie at first in the central cavity of the spermogonium and 

 remain there as long as it is kept dry. If the water finds its way in, the jelly swells 



FIG. 101. Collema microphyllum. A transverse section through the thallus ; A the hyphae, g the Algae (see 

 section CXVI), a the trichogyne projecting above the surface 'of the thallus; the spirally twisted archicarp which is 

 imbedded in the thallus terminates in the trichogyne. B a younger archicarp drawn separately. C, D 

 summits of trichogynes with spermatia attached projecting above the surface of the thallus which is shown by the 

 horizontal lines. After Stahl. A magn. 350, the rest 750 times. 



and forces them out of the neck on to the surface of the thallus, over which they are 

 distributed if there is sufficient moisture, as can be seen by transferring them to a 

 drop of water on a microscopic slide, where they move in a slow uncertain manner, due 

 no doubt to the currents in the dissolving jelly. 



The formation and discharge of the spermatia usually precede the appearance of 

 the commencement of the apothecium, as will be noticed again below. These, the 

 archicarps or carpogonia, are formed in most species of the group, in Collema, for 

 example, beneath the surface of the thallus, and singly as lateral branches from hyphae 

 which have nothing else to distinguish them. They are rather broader than the 

 parent-hyphae and coil up near their point of origin, forming usually two or three narrow 

 turns of a spiral, and then lengthen at the free extremity into a straight or slightly 

 curved filament, which grows towards the surface of the thallus and out beyond it into 

 the open air ; here it often forms a narrow flask-shaped expansion and ceases to grow 

 in length when the portion outside the thallus is about from four to six times as long 

 as broad (Fig. 101). 



