RicE: INTERNAL SORI OF *PUCCINIA SORGHI 43 
is little distortion of the cells below. The intercellular spaces 
are packed with hyphae, from which many small haustoria enter 
the cells. In the large-celled tissue also, although the inter- 
cellular spaces are filled with hyphae, there has been little crowd- 
ing apart of the cells. Therefore the group of internal sori 
stands out sharply in the parenchyma region between the two 
primary bundles already mentioned as the limits of the external 
sorus. Each sorus is intracellular and the host cell is not only 
isolated by intercellular hyphae but is lined with a hyphal felt, 
thus giving to each sorus the appearance of a more or less 
complete hollow cyst. All stages of development of these cysts 
are present. Many cells show simply the small haustoria which 
penetrate from the intercellular hyphae while the host nucleus 
when present shows a delicate chromatin net-work and a densely 
stained nucleolus. Other cells contain long hyphae running 
parallel to the wall. These seem to enter by a break in the wall 
closetoanintercellular space. In certain cells there is a pseudo- 
parenchymatous wall consisting of a close woven felt of hyphae 
lining the inside of the cell wall, adnate to it, and clearly distinct 
from the hyphae which fill the intercellular spaces around the 
cell. Such so-called cysts may occur singly, or as aggregates of 
several cells whose boundaries persist. In some cases the central 
space of such a cyst is filled by teleutospores of irregular shape 
due to crowding. Again normal teleutospores, complete even to 
their specially thick end-walls, are borne in a tuft projecting 
into the cell lumen from one corner of the cell (Fic. 2). The 
conditions agree with those described, in the following words, by 
Reynolds (17) for the infected Xanthium leaf, except that he does 
not mention the intracellular position of the cysts. 
Within the mixture of parenchyma cells and mycelium which replaces 
the normal tissue there are cyst-like bodies which are composed of masses of 
mycelium. These are hollow spheres and from the inner surface arise telial 
spores exactly similar to those borne in the normal way upon the exterior of 
the leaf. 
There is in the corn no trace of host cell contents in the cysts, 
although in some nearby cells encroached upon by intercellular 
hyphae a granular disintegrated mass remains. 
A second instance of internal teleutospores was found in a 
leaf sheath which was heavily encrusted on both surfaces with 
teleutosori (FIG. 3). In this case, in the interior of the leaf be- 
