GLOSSARY 519 



Mutualistic (Mu-tu-al-is'-tic) , relating to mutualism, the living together of 



two different kinds of organisms for the benefit of both, 132. 

 Mycelium (My-ce'-li-um), the threadlike growth, simple or branched, which 



forms the vegetative part of the fungi, 137, 273. 

 Mycorhiza (My-co-rhi'-za), the structure formed by the close life relation 



of fungi, or bacteria, and the roots of higher plants, 129-132. 

 Nectar gland, a gland, usually in flowers, which excretes a sweetish substance 



called nectar, 187. 

 Nectary, a nectar gland, 187. 

 Neuter, term sometimes applied to neutral or " sterile" flowers, i.e., those 



without stamens or pistils, 170. 



Neutral, said of flowers in which both stamens and pistils are absent, 145, 170. 

 Nitrification, the fixation of nitrogen, either free or from unstable com- 

 pounds, particularly through the action of microorganisms, 126-130. 

 Nucellus (Nu-cel'-lus), the inner part of the ovule, surrounded by the in- 

 teguments, 9, 15, 200-202, 391, 392, 395, 411, 416. 

 Nucleolus (Nu-cle'-o-lus), a small rounded body within the nucleus, 233, 



234- 

 Nucleus (Nu'-cle-us) , a densely granular body within the protoplasm of a 



cell, a special organ of the cell or protoplast, 4, 233, 234, 244, 245, 247, 



2 48, 253, 331. 



Ontogenetic (Ont-o-gen-et'-ic), relating to the development of the indi- 

 vidual, its evolution from the egg, 487. 

 Oogonium (O-6-go'-ni-um), the egg case, or female sexual organ, of certain 



algae and fungi, 242-248, 251, 259, 260, 281, 284, 285. 

 Oospore (O'-o-spore), the fertilized egg where a small sperm nucleus unites 



with the nucleus of an egg, 243, 244. 

 Operculum (O-per'-cu-lum) , the lid at the apex of the capsule of many 



mosses, 349. 

 Ovary, the portion of a pistil which bears the ovules, 13, 19, 144, 152, 156, 



160, 163, 165, 169, 177, 181, 185, 205, 405, 409. 

 Palet, the upper bract which with the flowering glume (lower bract) encloses 



the flower in the grasses (Gramineae), 173-177. 

 Papilionaceous (Pa-pil-io-na'-ceous), butterfly-like, said of flowers, like 



the pea, bean, etc., 146, 163, 166. 

 Pappus (Pap'-pus), the rudimentary calyx lobes in the form of chaff, scales, 



or threads, present in certain members of the compositae as in the 



sunflower, dandelion, etc. 

 Paraphyses (Par-aph'-y-ses), in the mosses, sterile rows of cells mixed with 



the antheridia, 348. 

 Paraphysis (Par-aph'-y-sis, plural, paraphyses), sterile threads parallel with 



the asci in certain fruit bodies of the ascus fungi and some basidium 



fungi, 300. 



