102] CURRENT LITERATURE 317 
PROFESSOR HEGLER’S work on the Cyanophyceae*} has been expected 
ever since 1895, but poor health delayed the investigation. After the 
author's death, the manuscript, quite ready for the press, was published by 
Professor G. Karsten, who states that after the appearance of A. Fischer's 
work the author most carefully re-examined the disputed points, but without 
_ deeming it necessary to change his views. The photomicrographs with which 
the paper is illustrated do but scant justice to the beautiful preparations 
which the reviewer had the privilege of examining. About forty pages are 
devoted to a critical review of the literature of the subject. The rest of the 
Paper, about eighty pages, contains an account of Hegler’s prolonged inves- 
tigations. The principal conclusions are as follows. There are no naked 
Protoplasts in the Cyanophyceae, all cells being provided with cell mem- 
branes, which in the heterocysts consist of cellulose, and in the other cells 
— principally of chitin. In the protoplast, or cell contents, may be dis- 
Mrwoles are never found in the colorless, central portion of the cell. The : 
__ 4 €rystals are particularly abundant in the heterocysts and spores, 
ate often entirely lacking in rapidly-growing vegetative CO 
Whether a nucleus is present or not is the most important morpho- 
‘a. sstion in connection with the Cyanophyceae and bacteria, since 
foc tht only organisms in which a nucleus has not been positively iden- 
ue bearing of this question upon present morphological theories of eS 
a seg Since previous methods have failed to solve the prob- oe 
w€ author devoted much attention to fixing and staining, and coumspeg 
Cet, alcoho} wing : Saturated aqueous solution of SO?, 7 parts; 4 Pe oe 
,_, . 93 Parts; mix just before using and fix for 12-24 hours; wash 
10 uae in water, and add glycerin 125 parts, 94 Per Ce” 
oS Parts, and saturated alcoholic solution of haematoxylin 25 parts: 
2ell Serle Untersuchungen iiber die Organization der Phycochromi 
oe Wiss. Bot. 36: 229-254. pls. 5-6. 1901. ae 
