266 Ethel McLennan : 



aleurone layer at this end of the grain cut tangentially, and tliere- 

 fore it does not appear as a single layer of cells.) Interpolated be- 

 tween the aleurone cells, lying in the inter-cellular spaces, alter- 

 ing their whole contour, are outlines of hyphae, which seem to Ijo 

 swollen, somewhat gelatinised, and in a state of disorganisation. 

 Similar bodies were also visible in the matrix of the cells them- 

 «elves. ^ 



These occurrences lead me to believe that at some stage in the 

 life of the grain tlie hyphae were intra-cellular, and that in the 

 few aberrant cases met with this embryological condition persisted 

 in the mature grain. 



Developmejit of the Ovary from the Flowering to the Fridtijig 



Stage. 



It is convenient to divide this portion of the paper into sections, 

 and to consider the relation of the fungus to the grain, at certain 

 •definite stages in its formation, lliis relation becomes very pro- 

 nounced and characteristic; either just about the • fertilisation 

 period or immediately afterwards, and from here to the final stages 

 is most intimately associated with the changes taking place, result- 

 ing in the formation of the endosperm, with its aleurone layer, and 

 the various parts of the embryo. 



Stage A. 



Text-figure 4 illustrates the external appearance of the 

 ovary at the flowering stage just prior to fertilisation. It is 

 drawn from the ventral surface, and shows the stigmas arising from 

 the dorsal side, the bi-carpellary nature of the fruit is indicated in 

 the figure. The ovum lies directed towards the< proximal end of the 

 ovary. I have designated this period Stage A. 



Hyphae are present in the carpels from their earliest inception, 

 but it is only at about this stage that their intimate relation with 

 the ovarian tissues of the grass is evident. They enter the ovary 

 at the stalk end, and brancli through the carpellary wall. They 

 are generally more abundant during the earlier stages at this end 

 than at the distal stigmatic end. These hyphae characteristically 

 accompany the vascular tissue of the stalk, and are to be seen in 

 very close proximity to the annular and spiral vessels running m 

 this area. (Plate XXI. Fig. 4.) In many of the sections numerous 

 small lateral buds on the hyphae suggested haustoria, but they may 

 be minute lateral branches just being caught in the section. The 



