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occurs no such root hairs develop. We are not at liberty to in- 

 fer from this that the plant has lost the ability to produce them, 

 because what occurs after the germination of the seed would pre- 

 vent the young epidermal cells of the root from extending them- 

 selves into hairs after the normal method. 



What happens really is this: Shortly after the development 

 of the little roots, and before the time for the root hairs, a fungus 

 hypha attaches itself to the young root not far from the tip. 

 This hypha thread, after fixing itself firmly to the root, grows 

 with great rapidity, branches and rebranches, winding itself 

 about the root and forming a complete network around it. As 

 it increases in age it forms a so-called pseudo-parenchymatic tis- 

 sue, by means of numerous partition walls. This new tissue, en- 

 casing the root, is small celled, thin walled and smooth on its sur- 

 face, except that hyphae are sent out from various parts which 

 extend into the soil, fasten themselves upon the little particles 

 in exactly the same manner as the real root hair. As the 

 growing tip of the root prolongs itself, thus developing a new, 

 fresh surface not covered by the fungus, new branches grow out 

 from the parts nearest the tip, and after a time grow f^ist to this 

 as in the older root So there is always a little part of the grow- 

 ing root tip free from the fungus, and ahvays a little zone around 

 which the fungus is coiling, but has yet no genetic connection 

 with the root. 



Back from this zone the fungus hyph^ are grown fast to the 

 epidermal cells, penetrating the walls and entering into the side 

 walls of these cells, but never into their lumen. As Frank de- 

 scribes it, the fungus hyph^ are grown fast to the tissues of the 

 root just as the hyphse of the lichen are grown fast to the Algse. 

 This combination of fungus hyph^ and root has been named 

 Mycorhiza or fungus root. This curious instance of parasitism, 

 or whatever name may be given it, has excited no little discus- 

 sion on the part of the professors forming the society known as 

 the Deutschen Botanischen Gesellschaft, at Berlin. Frank, who is 

 professor in the Landwirthschaftliche Hochschule, or" agricultural 

 college, is inclined to take the extreme. view, and actually goes 

 so far as to claim that the lofty tree, with its sweeping branches 

 laden with innumerable little work shoos for the manufacture o( 



