EXPLANATION OF TERMS. 



497 



Membranous layer. Same as mem- 

 branous mycelium. 



Membranous mycelium. Mycelium in 

 which the hyphae form by interweaving 

 a membranous layer. Same as mem- 

 branous layer, mycelial layer. Comp. 

 filamentous mycelium, membranous 

 mycelium. 



Mentagra parasitica. Same as sycosis. 



Merispore. Segment of a sporidesm. 



Meriatem. Actively dividing cell-tissue. 



Meristematic. Consisting of meristem. 



Meristogenetic. Produced by a meristem. 



Metabolism. The chemical processes 

 inseparably associated with the vital 

 activity of protoplasm. 



Metoecious. Forms which pass through 

 separate sections of their complete de- 

 velopment upon different hosts are me- 

 toecious. Same as metoxenous, hete- 

 roecious. Comp. autoecious, lipo- 

 xenous. 



Metoxenous. Same as metoecious. 



Microcyst. In Myxomycetes : a resting 

 state of the swarmcells. 



Microgonidium. Small gonidium com- 

 pared with others produced by the same 

 species. Comp. macrogonidium. 



Micropylar. Belonging to the micropyle. 



Microsoma. Small granule embedded 

 in the hyaline plasm of protoplasm and 

 constituting an essential portion of its 

 substance. 



Monoecious. Having male and female 

 organs on the same individual. Comp. 

 dioecious. 



Monopodium. An axis of growth which 

 continues to grow at the apex in the 

 direction of previous growth, while lateral 

 structures of like kind are produced 

 beneath it in acropetal succession. Comp. 

 dichotomy, sympodium. 



Multilocular spore. Same as sporidesm. 



Muscardine. Disease of the silkworm 

 caused by Botrytis Bassii. 



Mutualism. Symbiosis in which two 

 organisms living together mutually and 

 permanently help and support one an- 

 other. 



Mycelial layer. Same as membranous 

 mycelium. 



Mycelial strand- See fibrous mycelium. 



Mycelium. Vegetative portion of thallus of 

 Fungi composed of one or more hyphae. 



Mycetogenetic. Produced by Fungi. 



Mycetogenetic metamorphosis. Defor- 

 mation of parts due to Fungi. 



Mycosis. A disease of animal tissues due 

 to the vegetative activity of species of 

 Eurotium. 



Myxamoebae. In Mycetozoa : swarm- 

 cells with purely amoeboid creeping 

 motion. 



Neck. In Pyrenomycetes : conical or 

 cylindrical prolonged apex of pyrenocarp 

 through which runs the canal leading to 

 the ostiole. Same as tubulus. 



Nucleus. See kernel. 



Obligate. Necessary, essential. Comp. 

 facultative. 



Obligate parasite. An organism to which 

 a parasitic life is indispensable for the 

 attainment of its full development. Comp. 

 facultative saprophyte, facultative 

 parasite. 



Ontogeny. Development of an individual. 



Oogamy. Conjugation of two gametes of 

 dissimilar form. Comp. isogamy. 



Oogonium. Female sexual organ usually 

 a more or less spherical sac, without the 

 differentiation into neck and venter of 

 archegonium, and containing one or 

 more oospheres (ova). The oospore does 

 not divide to form a proembryo within 

 the cavity of the oogonium on the parent 

 plant. 



Oosphere (egg, ovum). Naked nucleated 

 spherical or ovoid mass of protoplasm 

 which, after its nucleus has coalesced 

 with the sperm nucleus, developes the 

 oospore. 



Oospore. Immediate product of fertilisa- 

 tion in oosphere. 



Ostiole (ostiolum). In Pyrenomycetes : 

 aperture in pyrenocarp through which 

 discharge of spores takes place. Same 

 as pore. 



Outer peridium. See peridium exter- 

 num. 



Ovule. In Phanerogams : macrosporan- 

 gium. 



Panicle. Twice or more branched struc- 

 ture in which the base of each branching 

 is elongated. 



Paniculate. Having the form of a panicle. 



Paraph yses-envelope. In Uredineae : 

 same as peridium. 



Paraphysis. Sterile capilliform hyphal 

 branch accompanying spore-mother- 

 cells in a hymenium. Applied by Phoebus 

 especially to a cystidium. 



Parasite. Organism living on or in and 

 at the expense of another living organism 

 (host). Comp. saprophyte. 



Parthenogenesis. Form of apogamy in 

 which the oosphere (ovum) itself de- 

 velopes into the normal product of 

 fertilisation without a preceding sexual 

 act. 



Pathogenous. Producing disease. 



Pebrine. Disease of the silkworm 

 caused by Nosema Bombycis, Nag., 

 a bacterioid organism. Same as gat- 

 tine. 



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