352 Fungi. Bacteria und Pathologie. 



Salmon, Ernest S., On Endophytic Adaptation shown 

 b V Eiyslplie Gramlnis DC. underCultural Conditio ns. 

 (Phil. Trans. Royal Society. Series B. Vol. CXCVIIL 1905. 

 p. 87—97. 1 Plate.) 



The author has recently pohited out, that certain species of Ery- 

 siphaceae are able under cultural conditions to infect theu* host plants, 

 when conidia or ascospores are sown on the cells of the internal tissues 

 exposed by means oi a wound, although the fungi in question are con- 

 iin'ed normally to the external surface of the epidermal cells. 



The present paper deals with the question of the growth of the 

 fungus under these abnormal conditions; the extent the hyphae penetrate 

 into the intercellular Spaces oi the internal tissues, and whether haustoria 

 are produced by these hyphae. With the exception of Phyllactlnia the 

 Erysiphaceae so far as they have been investigated, have been found to 

 be strictly ectoparasitic in habit^ the hyphae of the myceliuni being con- 

 tined to the external surface of the epidermal cells (never gaining access 

 to the intercellular spaces of the internal tissue) and merely sending 

 haustoria either into the epidermal celis alone, or, in the case of one 

 species, into the sub-epidermal cells as well. 



The author's summary of his work is much as follows. Young 

 leaves of oats and barley were cut off from seedling plants and a minute 

 piece of tissue was cut out from the upper surface of the leaf. In this 

 Operation the upper epidermis was renioved, and oiten a considerable 

 amount of the mesophyll also, so that in inoculation the conidia were 

 sown on the subepidermal or deeper layers of the exposed mesophyll. 

 After inoculation, the leaves were placed on damp blotting-paper in a 

 petri dish. By the sixth to eighth day vigorous infection had nearly 

 always resulted, the surface of the wound bearing patches of clustered 

 conidiophores. 



It was found on examining such wounded leaves that the fungus 

 had invaded the internal tissues to a remarkable extent. Where the 

 mesophyll cells that remained uninjured were several layers deep, the 

 hyphae had penetrated inwards^ winding through the intercellular spaces 

 as far as the internal surface of the lower epidermis. Haustoria were 

 sent into the cells of the superficial layer of the mesophyll by the hyphae 

 creeping on the surface of the wound, and into all the deeper layers of 

 the mesophyll by the hyphae running in the intercellular Spaces. The 

 sheath cells of the vascular bundles were much invaded by very vigorous 

 haustoria. The haustoria were normal in appearance. The hyphae 

 enclosed in intercellular spaces, either just below the surface of the 

 wound or deep down in the internal tissues, struggle to produce conidio- 

 phores. The respiratory cavities over the stomata of the lower epider- 

 mis were in a great number of cases füll of vigorous hyphae producing 

 young conidiophores. The direction of growth of the conidiophores 

 produced in the respiratory cavities and other intercellular spaces was 

 usually vertical. 



Figures are given showing the details of the growth of the hyphae 

 in the interior of the leaf^ and the production of haustoria and inter- 

 cellular conidiophores. 



The author reviewing the results of the investigations points out 

 that they afford a proof that E. gramlnis is not, as perhaps might have 

 been expected, so highly specialized as an ectoparasite as to be neces- 

 sarily restricted for its food supply to cells of the epidermis; but shows 

 itself capable of immediate adaptation to conditions closely resembling 

 those obtaining in endophytism. 



This fact suggests the possibilily that under some circumstances 

 the mycelial hyphae of species of the Erysiphaceae which are normally 

 ectoparasites may penetrate into the internal tissues of their host plants 

 exposed trough wounds caused in nature by the attacks of animals or 

 by physical agency. It is pointed out, however, that the successful entry 

 of the hyphae might be prevented, either by the drying up of the super- 



