236 
NEIL E. STEVENS AND FRED W. MORSE 
Method of Selecting Material for Study 
The prevalence of the endrot fungus on the Howes variety in Massa- 
chusetts, its relatively late development in the fruit, its characteristic place 
of attack, and its ability to grow at low temperatures, were utilized in select- 
ing berries which were infected only by this fungus. About half a bushel of 
Howes, picked during September, 191 7, from the state experiment bog 
at East Wareham, Massachusetts, were placed in storage in a crate with 
slatted sides and bottom so that abundant aeration was obtained. These 
berries were allowed to remain in storage about one month at temperatures 
which ranged from 15° C. to 20° C. Late in October, 1917, these berries 
were sorted into three lots: (i) those showing a small decayed area close to 
the calyx which appeared to be typical endrot, (2) perfect berries with no 
indication of decay, and (3) injured berries or decayed ones which did not 
show endrot in early stages. Lot 3 was immediately discarded, and lots 
I and 2 returned to storage, the temperature of the storeroom at this time 
being from 10° C. to 5° C. 
On December 19, 1917, the storage lots were re-examined and material 
was selected for comparative study. This consisted of partly rotten berries 
from lot I (those which in October had shown incipient endrot) in which 
the rot had developed typicd:lly, and of sound normal berries from lot 2. 
Some of the berries were fixed immediately for microscopic study. Both 
lots were then stored at a temperature somewhat below 5° C, and portions 
were removed during January, February, and March. A few berries from 
each portion were fixed for microscopic study, and the remainder were used 
for chemical analysis. 
Histological Observations^ 
Fusicoccum piitrefaciens is evidently (Fig. 1, A) one of the fungi in which 
the hyphae often grow directly into the host cells, as distinguished from 
those fungi in which the hyphae grow in the intercellular spaces and either 
do not enter the host cells as does Rhizopus nigricans (7) , or develop special- 
ized haustoria which penetrate the cell walls. 
While microscopic study furnished no evidence as to the way in which 
the fungus breaks through the cell walls of its host, there is some indication 
that the hyphae grow rather more readily between or within the cells than 
through the walls, since the hyphae frequently grow for considerable dis- 
tances between the cells without breaking through and often branch at cell 
intersections (Fig. i, B and C). 
Moreover, the hyphae are often constricted where they pass through 
the cell wall (Fig. 2, A and B), and a few cases were found in which several 
2 The material for microscopic study was fixed in a solution consisting of equal parts 
of glacial acetic acid and absolute alcohol, imbedded in paraffin, and the sections cut from 
7 /i to 10 At thick. Several stains were used, safranin with Delafield's haematoxylin, and 
safranin with "light green" in clove oil proving especially useful. 
