8 HUMPHREY 



showed evidences of comparatively few hyphee which evidently 

 served to connect the more functionally active interior system 

 with those in the rhizoids and with the substratum. Thus far 

 the habit of growth of this fungus agrees quite consistently with 

 those described by Cavers.^ 



At about this period in its development one may observe, scat- 

 tered here and there throughout the infected zone, vesicles of 

 considerable size and presenting a variety of form. These ap- 

 pear as great enlargements of the hyphae and are full of rather 

 coarsely granular protoplasm (Fig. 6). This protoplasm has 

 within it minute nuclei, at first rather few in number but as the 

 vesicles become older and larger increasing in number until 

 they quite fill the interior of the vesicle. It was further found 

 that in some instances at least these vesicles are connected with 

 the exterior by hyphge (Fig. 8) and along the course of these 

 hyphae may be seen certain of these nuclear bodies. Whether 

 or not they make their escape to the exterior as zoospores could 

 not be demonstrated, but their development and subsequent be- 

 havior is suggestive. In his recent work upon the development of 

 Ophioglossmn pendulum and other members of the genus, 

 Campbell ^ has demonstrated the presence of thin-walled vesi- 

 cles in the endophyte. In these the behavior of the nuclei 

 resembles that occurring in the vesicles of the endophytic fun- 

 gus found in the Fossonibronia. In Fossombronia these vesicles 

 completely fill the host cells in which they occur, in some cases 

 causing a considerable distention of the cell. 



As stated above, the amount of chlorophyll or of starch and 

 other products of metabolism varies with the degree of infection. 

 Certain cells of the host seem packed with hyphae, and a micro- 

 chemical test fails to reveal any of the products of the normal 

 cell, and while a large part of the stem appears to be dying, 

 the leaves and the uninfected stem tissue seem to be vigorous 

 and unaffected by the presence of the fungus. Comparison of 

 infected plants with those entirely or nearly free from fungus in- 

 vasion seems to demonstrate that up to the vesicle stage of devel- 

 opment the growth of the host is not abnormally stimulated, in 



^Loc. cit., p. 32-33. 

 ' Campbell, 1907. 



