REPORT OF COMMITTEE ON PUBLICATION 



. Plat* I 



129 



Plate 2. Haustoria and mycelium of Plasmopara viticola. 



solves the sheath. Thus in many of the mature haustoria there may be 

 seen about the base a goblet-shaped collar pierced by the greatly attenuated 

 stem of the haustorium (PI. II, figs. 2 and 3). After penetrating the cell wall, 

 the terminal portion continues its growth for a certain period, never, how- 

 ever, completely filling the cell as is sometimes the case in certain of the 

 Erysiphaceae. It is this terminal, globose portion which constitutes the 

 absorbing area of the haustorium. 



In the meantime the plasma membrane of the cell is gradually pressed 

 back by the advancing haustorium and often may be very closely appressed 

 to the latter but never penetrated by it (PI. II, figs. 2 to 5). 



The haustorium is thin walled. The presence of the host cell wall about 

 the partially swollen tip or the space between the plasma membrane and the 

 haustorium may give the impression that the wall is thick as has been stated 

 by Istvanffi (1913) and others. The former states that the wall is sometimes 

 thin and sometimes very thick. It is evident that in the first instance he has 

 observed the condition in which the plasma membrane is closely appressed 

 to the haustorium and in the second, the encompassing sheath of host cell- 

 wall. 



