Structure, etc., of Epiphegus Virginiana. 395 



The up-going main column of the liaustorium 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 



