260 



SCIENCE. 



[N. S. Vol. XIX. No. 47G. 



Wetzel, Reinhard A., Supt. Science High School, 

 Fargo, N. D. 



WiLeox, Guy Maurice, Professor of Physics, 

 Armour Institute, Chicago, 111. 



Willett, James R., 434 W. Jackson Blvd., Chi- 

 cago, 111. 



Williams, Frank Blair, Ph.D., Assistant Pro- 

 fessor Civil Engineering, Union College, Schenec- 

 tady, N. Y. 



Wilson, Delonza Tate, Case School of Applied 

 Science, Cleveland, Ohio. 



Wiseman, Carl Marshall, Optician, 301 W. 

 Chestnut St., Louisville, Ky. 



Woods, Carl Fred, Dartmouth College, Han- 

 over, N. H. 



Zeleny, Charles, University of Cliicago, Chicago, 



SCIENTIFIC BOOKS. 



Ueher die Organization xmd Physiologie der 

 Cyanophyceenzelle und die miiotische Teil- 

 ung Hires Kernes. Von E. G. Kohl. 

 Jena, Gustav Fischer. 1903. Pp. 240, 10 

 plates. 20 mlc. 



This book, the result of several years of 

 work on this interesting group of algae on the 

 part of Professor Kohl, will probably clear 

 away definitely many of the clouds of doubt 

 and contradiction over the structure of the cell 

 of these plants. Professor Kohl applied his 

 attention first to one species, Tolypothrix 

 latana, until he had mastered the proper 

 technique, and had acquired exact knowledge 

 of its structure. Then he applied the same 

 intensive study to Anahcena catenula and 

 Nostoc cmruleum, afterwards testing his dis- 

 coveries on a large series of the most diverse 

 Cyanophycese. 



Many points of structure, especially those 

 bearing upon the shape and structure of the 

 resting nucleus, as well as its behavior during 

 division, were made the object of study in 

 cells stained in vivo, as well as in cells fixed 

 by various chemical reagents. The most im- 

 portant contribution to our knowledge is that 

 in regard to the nucleus. The author confirms 

 Biitschli's and Tlegler's contention that the 

 central body (Zentrall^orper) is the nucleus. 

 This organ occupies the center of the cell and 

 runs out in numerous tapering branches into 

 the surrounding cytoplasm, these processes 



often extending to the cell wall. As ordinary 

 fixation methods cause their immediate re- 

 traction, they usually have been overlooked. 

 The nucleus has no definitely staining de- 

 limiting membrane, nor does it contain a 

 nucleolus. In it, and in it alone, are con- 

 tained certain granules named by Kohl ' cen- 

 tralgranules (Zentralkorner) and thought by 

 him to consist of reserve stufis. The ap- 

 parent occurrence of these granules in the 

 cytoplasm is explained by their being often 

 found in the processes of the nucleus. Sim- 

 ilarly, granules belonging in the cytoplasm 

 sometimes appear to be in the nucleus, when 

 they are imbedded in cytoplasm between the 

 bases of the nuclear processes. The central 

 granules are identified by Kohl with Biitschli's 

 red grains, Nadson's Chromatinkomer, etc., 

 and with the Volutanskugeln of the bacteria. 



The cytoplasm contains various inclusions, 

 chief among which are the cyanophycin 

 granules (protein crystalloids), fat drops and 

 certain semi-fiuid bodies in the heterocysts 

 which are found to fill up the pits in the cell 

 wall at the point of attachment to adjoining 

 cells. 



According to many authors, this blue-green 

 cytoplasmic mantle between the nucleus and 

 cell wall is the single, cylindrical chromato- 

 phore. Kohl, however, combats this idea and 

 considers as chromatopliores the very nu- 

 merous minute, colored bodies about 0.6 ^ in 

 diameter scattered throughout the otherwise 

 colorless cytoplasm. In their reaction 

 towards stains they behave as do the chro- 

 matopliores of higher plants. A study of the 

 coloring matter of the cell shows that besides 

 chlorophyll and phycocyanin, there is also 

 always present carotin, the xanthophyll of 

 many authors, which is never absent where 

 chlorophyll is found, throughout the vegetable 

 kingdom. It is the combination of these 

 coloring matters in various proportions that 

 makes possible the great variability of color 

 of the different species, or even within the 

 species of this group. 



Instead of starch these alga; produce as car- 

 bohydrate the nearly related glycogen, storing 

 it, apparently equally distributed, in the cyto- 

 plasm and not in granules. 



