296 
W. E. AGAR. 
(3) The constancy of the position at which transverse seg- 
mentation takes place indicates a constant differentiation of 
the chromosomes in a lengthwise direction. 
(4) The presence of transverse constiictions or joints in 
chromosomes is not^ without special evidence, to be taken as 
an indication of hivalency, or of a future division plane. 
Explanation op Certain Terms. 
At the request of the Editor, I take this opportunity of reminding 
readers that Wilson’s ‘ The Cell in Development and Inheritance ’ 
contains an excellent glossary. The few distinctively cytological terms 
used above which are not to be found there or in the index of that 
book are given below. 
Diakinesis (V. Hacker, 1897). — The stage in the meiotic prophase 
following synizesis, in which the chromosomes are scattered widely 
apart in the nucleus. 
Meiosis (J. B. Farmer and J. E. S. Moore, 1905).— The phase in 
which reduction of chromosomes takes place, including both maturation 
divisions. It is convenient to designate the stages of the first and 
second divisions as metaphase I, metaphase II, etc. (Gregoire). 
ISomatic should be restricted to mitoses in the cells of the body out- 
side the germ-track. By some authors this term is ajjplied to all 
mitoses outside the meiotic iDhase, including, therefore, those of the 
sperniato- and oo-gonia, but this misuse of the term is to be deprecated. 
Synizesis (C. E. McClung, 1905). — The clumping togetlier of the 
chromatin often observed in the meiotic prophase. It was included in 
Moore’s term, “ synapsis.” 
Teleutosyndesis (V. Hacker, 1910). — A theory of chromosome 
conjugation, according to which the conjugants are i)ermanently united 
in tlie meiotic prophase. 
List of References. 
Agar, W. E. — “The Spermatogenesis of Leijidosiren paradoxa,” 
‘ Quart. Journ. Micr. Sci.,’ 57, 1911. 
Della Valle, P. — “ Osservazioni di Tetradi in Cellule Somatiche,” ‘ Atti 
della Reale Accad. d. Sci. Fis. e Mat. Napoli,’ xiii, 1908. 
Gregoire, V. — “ Les Cineses de maturation dans les deux regnes (Second 
memoire),” ‘ La Cellule,’ xxvi, 1910. 
et Wygaerts, A. — “ Reconstitution du noyau et formation des 
chromosomes dans les cineses somatiques,” ' La Cellule,’ xxi, 
1904. 
