FUNGI 



ir 



varying external appearance, and of a certain degree of differentiation of 

 tissue. This differentiation is exhibited in the formation of layers, some- 

 times pseudo-parenchymatous, adapted for special functions. They are 



Fig. 271. — Section through sclerote oi Sclerotinia Sclerotiortiin Lib., showing its cortical 



medullary tissue (x 375). (After de Bary.) 



commonly characterised by the bearing of spores, or special spore- 

 mother-cells, on definite regions and in more or less definite arrange- 

 ment. They form, as a rule, that portion of the whole organism which 



Fig. 272. — Simple sporophores of Pkytophthora infcstans de V>y. a, formation of first 

 spores (zoosporanges) at ends of branches : b, two ripe spores on each branch and a third 

 being formed ( x about 200). (After de Bar}-.) 



is popularly termed a fungus, such as the stalk and cap of mushrooms, 

 the peridium of puff-balls, and the like. The structure of these is, as 

 has been said, very diverse, and it will be found described in more or 



