434 Acton.— Observations on the Cytology of the Chroococcaceae . 
II. Recent Literature. 
The numerous papers which have appeared dealing with the cytology 
of the Cyanophyceae have been reviewed by so many authors, that it seems 
unnecessary to give an account of any but the more recent. 
The papers of Kohl (’03), Phillips (’04), Olive (’05), and Guilliermond 
(’05), all contain excellent reviews. A criticism of these four papers forms 
the subject of a special paper by Zacharias (’07). 
interest chiefly centres round the question of the presence or absence 
of a nucleus, and its behaviour during division if present. Kohl, Olive, and 
Phillips agree on the presence of a nucleus which divides mitotically ; 
though they differ on the question of the arrangement of the chromatin and 
on the details of division. It seems probable that both Olive and Phillips 
have mistaken central granules for chromatin. 
The rod-like chromosomes of Kohl can hardly be explained as central 
granules, though stained preparations, in which under a -pf objective only 
central granules can be seen, do sometimes under a objective show struc- 
tures simulating karyokinetic figures with rod-like chromosomes ; with the 
greater magnification the rod-like bodies are resolved into granules. 
Zacharias, who through the kindness of Dr. Kohl has been permitted to 
examine some of his preparations, believes that they are projections, &c., 
from the central body. 
Gardner (’06), who has investigated Oscillatoria limosa and O. splendida , 
two species upon which Kohl worked, states with regard to mitosis in 
these : ‘ The process in the nuclei of these two plants is purely and simply 
amitotic.’ He also makes the following statement in the course of a com- 
parative review of the papers by Kohl, Olive, and Phillips: ‘After very 
careful and prolonged investigation I am unable to subscribe to any of the 
conclusions just quoted concerning the mitosis of the nucleus in any of the 
Cyanophyceae upon which they have worked.’ 
Kohl believes that there are numerous small granular chromatophores, 
while Olive and Phillips agree that there is a single large chromatophore. 
All find granules of two kinds — central granules and cyanophycin granules. 
Fischer (’05), on the other hand, denies the existence of a nucleus, 
though he admits the presence of a single chromatophore. He maintains 
that the chromatin-like, pseudo-mitotic masses in the centre of the cell are 
due to the presence of ‘anabaenin’, which is found sometimes in chro- 
mosome-like masses and sometimes in granules (central granules of other 
authors). The anabaenin is a transformation product of glycogen, and 
there is a steady stream of glycogen from the chromatophore to the central 
body. He believes that this laying down of anabaenin in the centre of the 
cell is a means of removing the excess of carbohydrate material formed by 
the chromatophore. He states that anabaenin is a carbohydrate, thus 
