27-i Ethel McLentian : 



Until the endosperm commences to be formed, the fundus has- 

 been increasin<^' in amount at the expense of tlie nucellus, etc. 

 This increase is only a temporary one, for tlie hyphae now grow in 

 close contact with the endosperm cells. They enter them when 

 the cells are young and not fully formed, and are here seen to be- 

 come disorganised. The food material thus gained by the grass 

 is used in tlie preparation of the reserve store of fnod, which is 

 later to be deposited in this tissue. Plate XXII., Fig ."5, shows a 

 portion of the endosj^erm and the accompanying hyphae. lliis 

 fjectidu Avas stained with congo red, and the hyphae and proto- 

 plasm stain in the same way. Plate XXII. Fig. 4, also shows the 

 close union betAveen the fungus and tlie grass. This section was 

 stained oidy Avith gentian violet, and tlie hyphae could /je traced 

 more readily in tlie cell itself. Many of the disorganising tlireads 

 running in the host cells stained blue, and are shown in the figure, 

 the cells themselves lemaining unstained. Plate XXII., Fig. 5, re- 

 peats the structure shoAvn in the tAvo previous figures, but in addi- 

 tion it shows extremely Avell, lateral bi-anches, Avhich arise from a 

 hyplia I'unning parallel to the length of the endosperm, ami Avhich 

 enter adjacent cells of this tissue, yielding up their food to the- 

 embryo grass plant. 



The fungus is most al)undant in the region of the ovum, due 

 prob'ably to the fact that the lumen of the emliryo-sac begins to fill 

 first around the embryo. In this region the cells are long and 

 crescent shaped, and have very dense contents. 



The synergidae are still present, and tlieir alisorption is no doubt 

 the result of the activity of the fungus, a fact which may help to 

 explain the pronounced growth of hyphae always present in this 

 position. 



The ovum is Still undivided, although it has increased in size- 

 and the cytoplasm has become vacuolai-. 



In the intermediate stages betAveen B and f, the division of the 

 ovum and the subsequent groAvth of the embryo are points of 

 interest. The first di\'ision of tlie egg is generalh' transverse, at 

 right angles to the j^i'o-embryo, and each cell usually contains a 

 AA'ell-marked vacuole. The fungus ramifying in the nucellus in this 

 part of the sac comes into direct contact Avith the endosperm, which 

 forms a lining to the pocket in Avhicli tlie end^ryo groAvs. The 

 hyphae are unusually abundant, and are actively ti'ausferring food- 

 material from the various parts of the carpel to the endosperm in 

 this area. (Plate XXV., Fig. ].) These cells are later absorbed 



