1903.] NATURAL SCIENCES OF PHILADELPHIA. 359 



thus entered. The course of such hyphse from cell to cell is made 

 clearer by the contraction of the protoplasm from the cell wall. This 

 condition has been produced by drying and the protoplasm has been 

 plasmolyzed. Two hyphse enter the protoplasm of a cortex cell, 

 converge near the center of the cell, and then run to the opposite cell 

 wall, where just before passing through it they diverge from each other. 

 Another hyphse enters a cell, and in the center of it forks to form a Y 

 (PI. XVII, fig. 6&). Still other hypha? in transverse section grow 

 through the triangular intercellular spaces, forming perfect complexes. 



In the older sections, hyphse are seen of a larger size and with browner 

 walls than the finer hyphse above described (PI. XVII, figs. 2, 4). 

 These seem to take a general longitudinal or oblique course through 

 the cortex, because in several transsections studied these hyphse exist 

 as rings lying in the cells, having been cut across by the razor. Large 

 brown hyphse are seen in the lacunar intercellular spaces of sections 

 made at the base of mycodomatial swelhngs (PI, XVII, figs. 2 and 4). 

 These hyphse are the main trunks of those that pierce the cells and 

 grow into the protoplasm, for they produce smaller branches which 

 assume the colorless aspect of the finer hyphse already described 

 (PI. XVII, fig. 66). It is, therefore, clear that the apical portions of 

 the mycodomatia have fine hyphse with a few thicker strands, while 

 sections cut from the older and basal portions of the swellings have large, 

 brown, thick-walled, unicellular hyphse which run longitudinally and 

 obhquely. The larger hypha probably form the older and peren- 

 nating mycelium which, during the hfe of the metamorphosed second- 

 ary roots, seem to provide new and finer hyphse to the apical portion of 

 the branches of the mycodomatium. 



The larger unicellular hyphse, which can be followed across the large 

 irregular lacunar spaces formed by the rupture of the cortex in drying, 

 enter cortex cells where they branch by the formation of short rounded 

 sickle-shaped branches (PI. XVII, fig. 3). Several of these curved 

 branches may be formed from a single hypha. These may be looked 

 upon in the nature of haustoria. Sometimes these branches, especially 

 near the apical portion of the mycodomatia, become extremely fine, 

 and then they may grow between the starch grains imbedded in the 

 protoplasm, forming a meshed structure to be referred to later (PI. XVII, 

 fig. 6a). The larger number of these brown thick-walled hyphse 

 are found in the medio- and endocortex, and they almost fill both 

 the cells of these regions and the intercellular spaces. The cortex cells 

 are no longer living in these reigons, but by the growth of the parasitic 

 hyphse they have been destroyed as living cells. However, at the 



