80 MISSOURI BOTANICAL GARDEN. 



struction of the host cell the fungus gradually loses its con- 

 tent until finally nothing remains but the walls of the 

 hyphae. 



Granting the fact that the host cell is destroyed before the 

 fungus, the gradual disappearance of the latter must be 

 caused by agencies outside of that particular cell, for if it 

 were but a ceasing of living conditions the various stainable 

 parts of the fungus would remain in the cell for a long time. 

 However, numerous examinations of cells of this kind from 

 the oldest portions of the tubercle show only walls closely 

 packed together by the collapsing of the host cells where 

 they undergo no further change (f. 23). Whatever benefit 

 the host plant derives from the fungus must be obtained 



through the host cell while it is yet in a living condition, or 

 by the other living cells which adjoin the infected ones. Pos- 

 sibly the plant can acquire greater gain by suffering the loss 

 of a few cells for the good of many. 



THE TUBERCLES OF MYRICA. 



The amount of research that has been done on the tuber- 

 cles of Myrica is rather limited when it is compared with all 

 that may be found on the alder; due probably to the fact 

 that they were considered, for some time, to be caused by a 

 similar fungus. Brunchorst (6) was the first to mention the 

 tubercles on Myrica Gale and considered the fungus produc- 

 ing them so much like that in the alder that he called it 

 Frankia subtilis. Later, Moller (26) found that it differed 

 considerably and made it a new species which he called 

 Frankia Brunchorstii. 



Shibata (38) has m 



* 1X lllv ^ w ^ 



on the root-tubercles of Myrica rubra, his observations being 

 on fresh material and on some prepared according to modern 

 cytological technique. He describes the external and inter- 

 nal morphology of the tubercle, noting that the fungus con- 

 fines itself to a definite region, thus differing from the condi- 

 tion found in the alder and other forms. The differentiation 

 of the tissues begins in the meristematic region, where inter- 

 nal infection of the young cells takes place. At first the fun- 



of 



to 



