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stem is not more than ^th of an inch broad, quite circular, and nearly flat. If 

 sporidia are taken from the hymeniiim of this plant and placed on decayed vine 

 leaves in a moist chamber the process is as follows :— They throw out a fine 

 white mycelium from which sclerotia arise which are capable of enduring in a 

 dormant state for twelve months, when they produce new cups. This is the 

 simplest cycle of reproduction. But a course may he taken different to this ; 

 the mycelium, instead of producing sclerotia, may give rise to a growth called 

 Botr litis cinerea, which consists of tufts of fine grey filaments bearing on their 

 points globose spores termed conidia in great abundance. The conklia are capable 

 of germination when they produce either liotriitis cinerea or sclerotia ; if sclerotia 

 then the sclerotia njay produce either Botrytis cinerea or cups. Thus the cycle of 

 reproduction becomes very complicated, the first and simplest being sporidia 

 forming sclerotia, sclerotia producing cups, sporidia from cui^s producing sclerotia ; 

 the second may be sporidia producing Botrytis, Botrytis producing sclerotia, and 

 sclerotia producing cups ; the third may be sporidia producing sclerotia, sclerotia 

 producing Botrytis, Botrytis producing ^o^rj/^is again, even for several generations ; 

 the fourth sporidia producing sclerotia, sclerotia producing cups. It must not be 

 inferred, however, that this process takes place in all the allied species, it having 

 been satisfactorily proved only in this one. Some of the Discomycetes are re- 

 produced by a widely different method, which it is not our purpose on this 

 occasion to notice. I will now proceed to describe the course of reproduction in 

 one more fungus with which I must conclude, namelj% the Mildew of Wheat. 

 This fungus is a true parasite, attacking its host while in a living state, and 

 living at the expense of the sap and vitality of the plant, ultimately killing it. 

 The economic aspect of the question as to the loss every year to the farmer 

 caused by this fungus is one into which I shall not enter, but simply give a brief 

 sketch of its life history. It passes through three forms, each of which has been 

 placed in a different genus and regarded as autonomous species, Uredo linearis, 

 Puccinia (iraminis, uEcidium berheridis. Beginning with the Uredo, we find it on 

 the leaves and other parts of wheat in elongated masses of orange-coloured spores, 

 known to farmers as "rust." Under the microscope these spores are elliptic and 

 covered with minute asperities. They are produced from mycelium, whicli 

 occupies a position beneath the cuticle of the wheat, and when mature they 

 rupture the cuticle, and become exposed and disseminated. Each spore is capable 

 of reproducing others in the following manner : — It alights on an unaffected leaf, 

 and, if moisture and other conditions are favourable, it pushes out a mycelial 

 thread from about the middle of its longer axis, which, after making several 

 revolutions, corkscrew fashion, enters through a stoma into the tissue of the 

 wheat and so forms new masses. Now, inasmuch as the host plant dies in the 

 autumn, how does the Uredo survive to attack the wheat of the following year ? 

 Towards the end of the summer these Uredo spores produce resting spores in the 

 form of Puccinia graminis, known as mildew. This appears as linear black 

 masses pushing through the epidermis, and must have been seen by every one 

 passing through a wheat field. Under the microscope the spores are elliptic, dark 

 brown seen by transmitted light, but black by reflected liyht, divided transver.sly 



