CHAPTER IV 



a cottony mass. Soon, at definite points, root-like branches are sent 

 into the substratum, and the clusters of upright stalks appear. 

 Each one of these stalks enlarges at the upper end into a little sphere 

 into which dense protoplasm collects ; finally a convex partition con- 

 verts this swelling into a cell, and the protoplasm divides into many 

 spores. Ultimately the outer wall of the cell dissolves and the spores 

 float off in the air, leaving only the stalks and the collapsed inner 

 wall or partition. This is, of course, simply cell division, but there is 

 sometimes a union of two cells to form a resting spore. So in repro- 

 duction as well as in structure the mould resembles some filamentous 

 algae. Some botanists regard fungi of this type as degenerate algae 

 that have lost chlorophyll and the power of making their own living. 

 But the relationship of fungi to other plants, and their affinities 

 among themselves, are matters that are far from settled. Not only 

 this, but the life histories of many fungi are not known. The whole 

 subject is a difficult one, and genuine work with it is undertaken only 

 by specialists. Every civilized government recognizes the value of 

 work of this kind in the department of agriculture, and has in its 

 employ men whose lives are devoted to this branch of applied science. 



It is easy to impress children with the importance of this subject 

 and to stimulate their interest in it, by frequently calling their atten- 

 tion to these fuugi when they are visibly present on common plants. 

 Smut, for instance, on the flowers, (that is, on the tassels and ears) of 

 corn is of common occurrence. The life history of smut has been 

 only recently known. The black sooty mass consists of spores, at 

 least they are commonly called spores, but they do not germinate 

 directly on corn plants. They fall to the ground and send out 

 branches that produce quantities of very minute spores. Even these 

 spores cannot penetrate a mature corn plant ; they simply infest the 

 ground and lie in wait for seedlings. They can enter the tender 

 tissues of the seedlings, and, germinating there, they produce a char- 

 acteristic fungus mycelium, as this mass of vegative cells is called. 

 In this case the filaments of the nlycelium are so exceedingly delicate 

 that it has been difficult to detect their presence in the most careful 

 microscopic work ; but it has finally been discovered that as the corn 

 plant grows, this invisible foe steadily advances to the parts whence the 

 flowers are to arise. When the plant sends great supplies of nour- 

 ishment for the development of its own essential organs, the fungus 

 suddenly springs into great activity and uses these supplies for the 

 production of its own spores. 



Rose leaves in our gardens are likely to be infected with rust whose 

 spores are tound on the under sides of the leaves. At first only the 



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