[52 



LECTURE IX. 





differentiation into a firmer, more resistent, epidermal layer, contrasted with an 

 inner mass of tissue corresponding to the fundamental tissue, still recurs ; and that 

 where the relations of form otherwise admit of it, a bundle formed of parallel, 

 elongated elements runs in the fundamental tissue, which again is to be regarded 

 as the rudiment of a vascular bundle. 



Apart from the Mucorini and a few other non-cellular Fungi, the hypha, or 

 jointed fungus filament, is maintained with striking consistency as the elementary 

 form of histological structure in the Fungi. The hypha is a filament segmented 



by transverse septa, mostly very thin, 

 Y_,^^ _-,x growing forward at its end, and 



often much branched. In the so- 

 called Mould-fungi, the mycelium, as 

 well as the fructification, consists of 

 single hyphffi ; where, however, the 

 vegetative body is more massive, as 

 in the fungi commonly known as 

 Truffles, Mushrooms and Toad-stools, 

 Gasteromycetes, etc., the mass of 

 tissue, often variously differentiated, 

 is likewise composed entirely of 

 such hyphse. The tissue of these 

 plants is thus constructed, not, as in 

 the majority of Algae and all Mosses 

 and vascular plants, by means of bi- 

 partition and a corresponding forma- 

 tion of chambers, commencing ori- 

 ginally in the unicellular embryo 

 and proceeding with the growth ; but 

 the internal structure of the Fungus 

 gives the impression of very numerous 

 hyphae, each one of which strictly 

 speaking leads an independent exist- 

 ence, having become united into a 

 colony, the single individuals of which 

 — that is, the hyphae — are subordi- 

 nate, however, to a common plan of 

 configuration. Instead of detailed 

 explanations, the consideration of 

 the half diagrammatic Fig. 162 may give an idea of the facts indicated. In 

 spite of this structure, entirely deviating from the usual histological type, here again 

 a sharply marked differentiation of tissue nevertheless results: in Fig. 162 this is 

 expressed chiefly by the closely packed (and, as it seems, lignified or other- 

 wise altered) hyphae running on the surface of the tissue-body, representing an 

 epidermal tissue, to which even hair-like outgrowths are not wanting. ' Moreover, 

 we perceive how in the internal mass of tissue the hyphae bound certain spaces ; 

 of which the darker roundish portions enclose hollow chambers, in which the 



|,.;»,«#f' ,. 



Fig. 162.— Half of a longitudinal section through the fructification of 

 Cruciliiilnm ■vulgare (a Gasteromycete). ap the so-called outer, ip the 

 inner peridium ; these together constitute the skin ; j^^liairs. The figure 

 is diagrammatic in so far that the hyphae are represented far too thick. 



