FUNGI. INTRODUCTORY 405 



origin always a false tissue, or pseudo-parenchyma, made up from 

 independent filaments, not a true parenchyma produced by segmenta- 

 tion of cells with a common origin. Many Fungi form large solid 

 masses of such pseudo-parenchyma, which are called sclerotia, and 

 serve for storage during a resting period (Fig. 341). The hyphae are 

 limited by a cell-wall, composed of substance differing in its reactions 

 from ordinary cellulose : they may be septate or non-septate, and" in 



FIG. 340. 



Base of a young tree (s) killed by A rmillaria mellea, which has attacked the roots, 

 and developed rhizomorphs (r) and fructifications. To the right the fructifications 

 have been traced by dissection to the rhizomorphs that produced them. (After 

 Marshall Ward.) 



the former case there may be considerable variety in the number of 

 the minute nuclei in their colourless protoplasts. Chromatophores are 

 absent, and there is no starch, its place being taken by glycogen, or 

 by globules of oil. Thus structurally the cells of Fungi resemble those 

 of Algae, but without the chloroplasts or chlorophyll. 



The success of the Fungal nutrition, whether parasitic or saprophytic, 

 depends greatly upon their power of penetration of the nutritive 

 medium. It has been shown in various cases that this is due to a 

 digestive secretion, and the same probably applies generally. A 

 highly refractive drop may sometimes be seen on the end of the 



