GLOSSARY 443 



formed; opposed to the* "trophoplasm " or nutritive plasm. (STRASBURGER, 

 1892.) 



[Lanthanin] (\avOdvuv, to conceal), equivalent to oxychromatin. (HEIDENHAIN, 

 1892.) 



Leucoplas'tids (ACVKOS, white ; TrAaords, form), the colourless plastids of plant- 

 cells from which arise the starch-formers (amyloplastids), chloroplastids, and 

 chromoplastids. (SCHIMPER, 1883.) 



Li'nin (linum, a linen thread), the substance of the "achromatic" nuclear reticu- 

 lum. (SCHWARZ, 1887.) 



Lininoplast, the true nucleolus or plasmosome. (EiSEN, 1899.) 



Macrocentrosome, a term applied to the " centrosome " in Boveri's sense, i.e. to 

 the larger body in which lies the central granule. (ZiEGLER, 1898.) Probably 

 synonymous with entosphere. 



Maturation, the final stages in the development of the germ-cells. More spe- 

 cifically, the process by which the reduction of the number of chromosomes 

 is effected. 



Metakine'sis (see Metaphase) (/xera, beyond (i.e. further) ; Kiwrpris, movement), 

 the middle stage of mitosis, when the chromosomes are grouped in the equatorial 

 plate. (FLEMMING, 1882.) 



Metanu'cleus, a term applied to the nucleolus after its extrusion from the germi- 

 nal vesicle. (HACKER, 1892.) 



Met'aphase. the middle stage of mitosis during which occurs the splitting of the 

 chromosomes in the equatorial plate. (STRASBURGER, 1884.) 



Met'aplasm (perd, after, beyond ; TrAacr/jia, a thing formed), a term collectively 

 applied to the lifeless inclusions (deutoplasm, starch, etc.) in protoplasm as op- 

 posed to the living substance. (HANSTEIN, 1868.) 



Micella, one of the ultimate supra-molecular units of the cell. (NAGELI, 1884.) 



Microcentrosome, equivalent to the central granule or centriole of Boveri. 



(ZiEGLER, 1898.) 



Microcen'trum, the centrosome or group of centrosomes united by a " primary 

 centrodesmus," forming the centre of the astral system. (HEIDENHAIN, 1894.) 



Mi'cropyle (/XIK/OOS, small ; Trv\rj, orifice), the aperture in the egg-membrane 

 through which the spermatozoon enters. [First applied by TURPIN, in 1806, 

 to the opening through which the pollen-tube enters the ovule. /. ROBERT 

 BROWN.] 



Mi'crosome (/uucpo?, small ; o-w/xo, body), the granules as opposed to the ground- 

 substance of protoplasm. (HANSTEIN, 1880.) 



Microsphere, the central region of the aster (centrosphere) at the centre of which 

 lie the centrosomes. (KosTANECKi and SIEDLECKI, 1896.) 



Middle-piece, that portion of the spermatozoon lying behind the nucleus at the 

 base of the flagellum. (SCHWEIGGER-SEIDEL, 1865.) 



Mid-body ("Zwischenkorper"), a body or group of granules, probably comparable 

 with the cell-plate in plants, formed in the equatorial region of the spindle during 

 the anaphases of mitosis. (FLEMMING, 1890.) 



Mi'tome (/urctyio, from /uVog, a thread), the reticulum or thread-work as opposed to 

 the ground-substance of protoplasm. (FLEMMING, 1882.) 



[Mitoschi'sis (/UTOS, thread; crxt'etv, to split), indirect nuclear division; mitosis. 

 (FLEMMING, 1882.) 



Mito'sis (/M'TOS, a thread), indirect nuclear division typically involving: a, the 

 formation of an amphiaster; b, conversion of the chromatin into a thread 

 (spireme) ; c, segmentation of the thread into chromosomes ; d, splitting of the 

 chromosomes. (FLEMMING, 1882.) 



Mi'tosome (/AITOS, a thread ; o-w/xa, body), a body derived from the spindle-fibres 



