xxx GLOSSAKY OF TECHNICAL TEEMS 



MONOTREME (Gr. juoVos, single ; rp^a, aperture), a member of the 



primitive mammalian group Monotren&ta. 

 MULTICELLULAR (Lat. mnlti, many ; cellula, cell), composed of 



many cells. 

 MUTATION (Lat. mutatio, change), a suddenly appearing sport or 



variety, which breeds true. 

 NECTARY (Gr. vUrap, the drink of the gods), an organ in which 



honey is produced in a flower. 

 NEURON (Gr. vtvpov, string, nerve), a nerve cell with its attached 



fibre, a unit of the nervous system. 

 NOTOCHORD (Gr. i-wrov, back ; xP^> strm g)> a cord of cells around 



which the backbone is formed in vertebrate animals. 

 NUCELLUS (Lat. nucleus, kernel), an inner part of the ovule or 



immature seed, really a macrosporangium. 

 NUCLEAR MEMBRANE, the membrane which encloses the 



nucleus. 



NUCLEINIC ACID, one of the chemical constituents of the nucleus. 

 NUCLEOLUS (Lat. dim. of nucleus, kernel), a special aggregation of 



chromatin or other substance in the resting nucleus. 

 NUCLEOPLASM (Lat. nucleus, kernel ; Gr. TrAao-jua, formative 



material), the protoplasm of the nucleus. 

 NUCLEUS (Lat., kernel), a specialised protoplasmic body found 



in the interior of every typical cell. 

 ONTOGENY (Gr. ov t oWoj, a being ; rt. ytv-, birth), the life-history 



(development) of an individual organism. 

 OOCYTE (Gr. o>oV, egg; KVTOS, cell), an immature ovum ; a cell 



from which an ovum originates. 

 OOGENESIS (Gr. cooV, egg ; yeWo-is, origin), the process by which 



ova are formed in the animal K.dy. 

 OOGONIA^ (Gr. woV, egg ; yoVos, fruit), the female organs, containing 



the oospheres, in Fucus, &c. 

 OOGONIA (Gr. woV, egg ; yorevj, ancestor), the cells from which the 



oocytes arise in oogenesis. 

 OOSPHERE (Gr. woV, egg ; a-^alpa, sphere), a name frequently 



applied to the plant ovum. 

 OPHIUROID (Gr. otyus, snake ; ovpa, tail), a brittle-star or sand- 



star. 

 OPPOSABLE (Lat. opponere, to place opposite), a term applied to 



the thumb or great toe when capable of being placed with its 



tip opposite to those of the other digits. 

 ORDOVICIAN, one of the palaeozoic epochs of the earth's history. 



