IV. On endophytic adaptation shown by Erysiphe graminis DC. under cultural conditions

Abstract

I have recently pointed out (1) (2) (3) that if a small wound, removing a patch of epidermal cells, is made on the leaf or stem of certain host-plants, and conidia or ascospores of certain species of the Erysiphaceæ are sown on the cells of the internal tissues thus exposed, vigorous infection will take place, and in a few days the surface of the wound will be covered by a mycelium bearing densely clustered conidiophores with ripe conidia. The fact was somewhat surprising, since the fungi in question are confined normally to the external surface of the epidermal cells. It was desirable to ascertain the details of the growth of the fungus under these abnormal conditions, and to discover to what extent the hyphæ of the mycelium penetrated into the intercellular spaces of the internal tissues, and especially whether haustoria, normal or otherwise, were produced, and if so, in what cells they were formed.