1897.] The Advance of Biology in 1895. 785 
THE ADVANCE OF BIOLOGY IN 1895. 
By C. B. DAVENPORT. 
The publication of L’ Année biologique for 1895, which is de- 
scribed in another column, gives us an opportunity to make 
use of the admirable summaries of the chapters to summarize 
still further the advance of general biology in 1895. 
Oytology—The group of unnucleated organisms was still 
further diminished by Nadson’s discovery in Cyanophyces of 
chromatin-like granules diffused throughout the cell, but ar- 
ranging themselves during cell division in a way recalling 
karyokinesis. The idea of the permanent nature of the cen- 
trosome in the cell was strengthened by finding it in resting 
cells of many plant and animal tissues. The identity of cen- 
trosome and nucleolus in the infusorian Spirochona was in- 
sisted upon by Balbiani. 
In the study of cell-division we find the year characterized 
by the variety of material employed—the attempt to build up 
a broader comparative knowledge upon the basis of well-stud- 
ied types. The nuclear origin of the spindle was strongly 
maintained by Strasburger and others against the prevailing 
view. New variations in the method of splitting of the chro- 
mosomes were described. The mechanical (rather than the 
magnetic or chemotatic) explanation of the intracellular 
movements seemed to gain favor. The nature of the archo- 
plasm, whether a part of the cytoplasm or different, was left in 
debate. New intermediate conditions uniting direct and in- 
direct nuclear division were described and the great variety in 
the karyokenetic process was becoming generally recognized. 
The sexual products and fecondation—The question of chro- 
matic reduction before the introduction of new chromatin by 
fertilization attracted many workers, and new data were ob- 
tained on the number of chromosomes in different species, the 
time at which reduction takes place and the details of the 
method. New methods of formation of the tetrads by conju- 
gation were described by Wilcox, Calkins and others. 
