Structure, etc., of Epiphegus Virginiana. 395 
The up-going main column of the haustorium repeats the 
condition of the lower column. But it divides more irreg- 
ularly and soon sends out long slender extensions that 
stream out and up in every direction. In all cases, the haus- 
torial cells lie with their long axes parallel to the direction 
of each haustorial arm. The haustorium is always sur- 
rounded by several rows of simple flattened parenchyma 
cells. These may be Epiphegus cells compressed by the 
ingrowth of the haustorium, or they may be cells accom- 
panying that organ. They are seen passing over into the 
beech-root. They are well marked in the region where the 
haustorium has just entered the parasite, and thin out to a 
single row in the fine haustorial ends. 
These two haustorial columns formed in the upper region 
keep rising vertically for a considerable distance, after they 
have once reached the opposite sides of the tuber. Finally 
they are lost in fine endings. At this height the bundles 
have now assumed a rather regular arrangement, approxi- 
mating that of the aerial stem. There is now a fairly com- 
plete ring of separate, undifferentiated bundles. These 
bundles are better developed on the side away from the haus- 
torium. The haustorium finally has extended through fully 
two-thirds the entire height of the tuber. 
At the summit and somewhat on one side of the tuber its 
growing apex appears. It consists of a considerable area of 
small, densely stained embryonic cells, containing large 
nuclei and nucleoli. Overlying this region, there are in such 
a young plant but four overlapping scale-leaves. These are 
relatively very large, and cover almost the entire width of 
the tuber. 
The succeeding stages in the development of seedlings of 
Epiphegus have not been worked out. But from a brief 
examination of sections illustrating a number of these stages, 
it may be stated that on the lower part of the tuber new 
roots continually arise and elongate. The tuber elongates 
steadily, frequently bending its upper part around, if the 
