268 



Ethel McLennan : 



cells of the carpellary stalk do not contain starch, and many of 

 them stained deeply with the gentian violet after counter-staining^ 

 the sections with bisniarck brown. These blue cells were always 

 plentiful in this region ; such cells have been invaded by the fungus, 

 and their contents probably used for its own nutrition. They 

 always stain deeply, and the hyphae in their vicinity do likewise. 

 If the cells do not stain too darkly, it is possible to observe fungal 

 threads forming a network in the lumen of the cells, many of the- 

 threads being exceedingly fine. The position of these cells is shown 

 in Plate XX. The cells are not enlarged, and apparently only 

 differ from those around them by their different staining properties. 

 The cell walls in ^lis area are pitted; whether this is the normal 

 condition or whether the pit has resulted from a secretion of the- 

 fungus is a debatable point. 



The lateral walls of the carpel are packed with small compound 

 starch grains, and in this region the hyphae only occur between 

 the c:^lls. They run in all directions, but are, as far as I have- 

 observed, strictly inter-cellular in this position, at this stage. 

 However, when the stigmatic region is reached they seem to get the 

 upper hand, and a large number of cells become their prey. These 

 cells are also starch-containing, and when so intruded upon they 

 immediately react to the violet stain. Sometimes the whole of this 

 area will appear a dense violet colour, for the great majority of 

 the cells in this part are attacked at this period. When the cell is-- 

 first invaded, the starch is seen to become swollen and disorganised, 

 and loses its power of reacting to the iodine wash used in prepar- 

 ing the sections (Plate XXL, Figs. 2 and 5). The fine hyphal 

 threads wrap round the starch groups, and even enter between 

 each individual grain (Plate XXI. Fig. 5), apparently digesting 

 them. There is no doubt that these cells are suffering at the hands 

 of tlie fungus, and that their contents are being transferred to this 

 fungal system. Some of the cells shoAv an entire absence of starch; 

 they appear to be practically empty, and somewhat collapsed. 

 These have been invaded at an earlier stage, and yielded their con- 

 tents in a similar way. The stigmatic tracts present in the carpel 

 Avail generally show hyphae in abundance; they extend right into- 

 the stigmas, and even here become intra-cellular, but do so probably 

 only arcer fertilisation has taken place, when the function of the 

 stigmas has been completed. 



Occasionally, the base of a staminal filament remained attached 

 to the ovary during sectioning, and hyphae were found to extencJ! 



