THALLOGENS FINISHED. 



29 



^ Fig. 19. — Potato-rot. (Perorwspora £«/e«inns) : stipe pro- 

 ceeding from stomata of the potsito-leaf; mycelium 

 creeping through the leaf-tiBsue. Much magnified. 



scopie, especially in the moulds, one species of which (Fig. 

 18) forms Beer- 

 Yeast; another 

 (Fig. 19) is the 

 Potato-rot; another 

 (Fig. 20) lives on 

 fruit, paste, etc., 

 which is beginning 

 to spoil. 



52. Among the Mil- 

 dews are the Wheat- 

 blight (Puccinia), Smut 

 (Ustilago), and Ergot 

 (Cordiceps, Sphseria). 

 Close to these is the 

 Truffle (Fig. 21). It is 

 hypogeal, loving chest- 

 nut woods. It is com- 

 mon in Southern Eng- 

 land and the southern parts of Europe. Here is the edible Morel 

 (Morchella). Many of the plants of this 

 division are of a brilliant scarlet or orange. 



53. The Slime-Moulds (Myxomycetes) 

 are included in the Fungi. They shovf us 

 the simplest form of vegetative life, — a wan- 

 dering mass of Plasmodium* (shapeless pro- 

 toplasm) without cell-walls. This mass 

 moves .slowly, growing 

 sometimes to the thick- 

 ness of an inch, and cov- 

 ering considerable sur- 

 face. After a certain period the plasmodium passes 

 into a state of rest, and forms itself into masses ; 

 each mass develops into sporangia, of various 

 forms according to the genus ; many of these con- 

 tain a Capillitium, which is a net-work of threads, 

 often very beautiful. Their spores are elegantly 

 grouped, like those of the Mushrooms, on oblong 

 or conical cells ; each of these cells (called a 

 Basidium — basis, or pedestal) has two or four 

 slender points [sterigm.ata, sing. sterigm.a), 

 each point bearing a spore. This floral devel- 

 opment places them, therefore, notwithstand- 

 ing their simple vegetative structure, close to the Mushrooms 



Fio. 20. — Common Mould 

 (Mucor mricpdo), showing my- 

 celium, stipe, and receptiicle. 



Pio. 21.— Black Truffle 

 (Tuber melanosporum). 



* Closely resembling Protozoa (first animals). Plasmodium resem- 

 bles the wandeiing . sarcode (flesh protoplasm) of Amceba, and other 

 Protozoa (5). 



3* 



