Fiingua of Lolium, 259 



transverse section nearer the pioxinial end oi the grain, as is 

 shown in Fig. 2, would cut- througli tlie scutelluni. Such a section 

 shows that the hyphae occur between the endosix^nii and the scutel- 

 luni wherever the tissues are in contact, and hyphal penetrations 

 into the scutelluni may and do take place at any point over this 

 area. The hyphae in addition extend even jiast the limits of the 

 aleurone layer, and penetrate the sGutellum on its outer exposed 

 dorsal surface. A transverse section at the extreme proximal end 

 of the grain, Fig. ,S, jiasses through the eml)ryo, l)ut the starcliy 

 endosperm is no longer included in the section. Even at this level 

 the hyphae surround the scutelluni, as is indicated by the yellow 

 line in the figure. The coronal plane is perhaps the best for demon- 

 strating the distribution of the fungus in any one section (Plate 

 XVIII. Fig. 4), the occurrence of the fungal layer between the 

 scutelluni and endosperm at all points of contact and the extension 

 of the fungal tissue on the dorsal proximal surface is clearly seen. 



Plate XVllI. Fig. 5, shows a median sagittal section illustrating 

 the same points and, in addition both of these latter sections shew 

 the distribution of the hypliae in the embryonic area. The scutelluni 

 is often very richly traversed by fine fungal threads, and they are 

 not restricted to any special area, but occur more or less uniformly 

 right through the tissue. Some grains show these threads more 

 readily than others, but a study of the embryology of the grain 

 will suggest that this might often be the case, llie hyphae are 

 readily discernible in the growing cone; their presence here has 

 been pointed out by the earliei- workers. (Text-figure 1.). The 

 above facts are also true of Lolium teinulentiim, but it is much 

 rarer in this case to obtain a scutelluni so markedly inhabited as 

 in Loliiun perenne, and in any case the threads are generally finer. 

 In several examples of Lolium perenne I have found hyphae present 

 in the radicle, but they are not generally evident in this re«rion. 



Freeman raises the question — How does the fungus obtain en- 

 ti-aiice to the embryo? As an an-swer, he devoted a large part of 

 his paper to a description of a localised i)atch of liyphae, which he 

 termed " tJie infection layer,'' and to its mode of origin. He says 

 that on the ventral proximal end of the grain there occurs an iso- 

 lat-ed patch of hyphae which penetrates betwt>en the aleurone cells 

 and cells of the scutelluni, and tliereby gain entrance to the 

 embryo Avhen it is fairly advanced in its develo])ment. He 

 states that on the dorsal surface of Ihc grain the hyphae 

 do not extend to the ond of the aleurone layer. To 



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