78 SUMMARY OF CURRENT RESEARCHES RELATING TO 
concentration of the chromatiu in threads, the movement of the threads 
to the equator, their longitudinal splitting, their divergence and arrange- 
ment in two daughter-nuclei, are all distinctive. But among the 
peculiarities, the author notes that the chromatin is always in thread- 
form, and that there is a peculiar “ nucleolo-centrosome.” This is an 
axial rod around which the chromosomes are grouped. It defines the 
direction of division, directs the movement of the chromosomes, and 
dominates the whole process of division. The relations of this nucleolo- 
centrosome to an ordinary nucleolus and to an ordinary centrosome 
remain obscure, but the author draws some interesting comparisons, e. g. 
between the division of Euglena and that of Diatoms. 
A peculiarly Abnormal Form of Cristsllaria.* — Sig. E. Dervieux 
describes a Piedmontese fossil form of Gristellaria Lmk., which unites 
in itself the characters of two species, G. fragaria Giimbel and G. cassis 
Fichtel and Moll. His interpretation is that a spore of G. cassis found 
lodgment on a specimen of G. fragaria , and used the old shell as a 
foundation for a new and different architecture. 
Dervieux also describes f a collection of Foraminifera from the 
Ampliistegina - zone near Pavone d’Allessandria. 
♦ Atti Accad. Pontific. Nuovi Lincei, xlviii. (1895) pp. 111-2 (1 fig.), 
f Tom. cit., pp. 113-5. 
