120 NATURAL SCIENCE [August 1898 
they are strung. An explanation far removed from current theories 
has forced itself on me—perhaps after all it is the achromatic 
plasma (‘linin’) of the nucleus whose fair and equal division is the 
important matter, the final cause of karyokinesis. But the splitting 
of a viscid thread is one of the most difficult mechanical feats to 
accomplish. Suppose, then, that there is a certain polarity about 
the granules of chromatin, through which, after their division, they 
tend to recede from their fellows as far as possible; through this 
they will determine a splitting of the filament on which they are 
strung. The close of nuclear division sees their task accomplished ; 
and, as we should expect, the chromatic granules having fulfilled 
this appointed task, now atrophy, and remain in this state till the 
approach of a new cell-division determines a fresh growth of their 
substance. According to this view the linin is the transmitter of 
inherited properties, and the chromatin has a purely mechanical 
function in karyokinesis. I may venture to predict that this 
hypothesis will be shortly incorporated into the newest edition 
of the germ-plasm theories; for it avoids the many difficulties 
due to the ascription of hereditary constancy to a substance so 
subject to periodic atrophy and growth as the chromatin of the 
nucleus. Marcus Harroa. 
QUEEN’S COLLEGE, CORK. 
LITERATURE REFERRED TO. 
Hartog, Marcus, ’91.—‘‘Some Problems of Reproduction: a Comparative Study of 
Gametogeny, and Protoplasmic Senescence and Rejuvenescence.” Quart. 
Journ. Mier. Sci., n.s., vol. Xxxiil., pp. 1-79. (Dec.) 
’97.—‘*The Fundamental Principles of Heredity.” Nat. Sci., vol. 
xi., pp. 233-239 and 305-316. (Oct. and Nov.) 
Hertwig, Oscar, ’90.—‘‘ Vergleich der Ei- und Samenbildung bei Nematoden. Eine 
Grundlage fiir cellulire Streitfragen.” Arch. Mikr. Anat., vol. xxxvi., pp. 
1-138, pts. i.-iv. 
Strasburger, E , 94a.—‘‘ The Periodic Reduction of the number of the Chromosomes in 
the Life-history of many Organisms” [translation of a paper read at the Oxford 
Meeting of the British Association]. Ann. Botany, vol. vill., pp. 281-316. 
(Sept. ) 
’94b.—Ueber periodische Reduction der Chromosomenzahl im Entwick- 
lungsgang der Organismen [the original paper from which the former was 
translated, but revised and extended after the discussion thereon in Section D. 
at Oxford]. Biol. Centrailbl., vol. xiv. pp. 817-838 and 849-866. 
