GLOSSARY 443 



formed; opposed to the •' trophoplasm " or nutritive plasm. (Strasburger, 

 1892.) 

 [Lanthauin] {Xavdavuv. to conceal), equivalent to oxychromatin. (Heidenhain, 



1892.) 

 Leucoplas'tids (Aev/cds. white : TrAaards, 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 01 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. iMore spe- 

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

 is effected. 



Metakine'sis (see Metaphase) (^lera, beyond {i.e. further) ; Kivvqai^, movement), 

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

 plate. (Fle.mmixg. 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 (/^era. after, beyond; 7rAao-/xa, 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.) 



Microceutrosome. 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 (/^tfcpos, small; ivvXr], 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 

 Brow^x.] 



Mi'crosome (/u,tKpds, small : craj^a, 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 tlie 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 ("Zwischenkbrper"), 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 (/xtrw/xa, from /xtro?, a thread), the reticulum or thread-work as opposed to 



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

 [Mitoschi'sis (fxiro^. thread; o-xt^en', to split), indirect nuclear division; mitosis. 



(Flemming, 1882.) 

 Mito'sis (/xiTos. a thread), indirect nuclear division typically involving: ai, the 

 formation of an amphiaster: /', 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-uJ/xa, body), a body derived from the spindle-fibres 



