348 Journal of Applied Microscopy. 



powers of distinguishing the kinds of granules found in living cells. The authors 

 consider these granules as specific cell secretions which can be discharged : the 

 "mast cells'" showing this feature most distinctively. a. m. c. 



Held, H. Structure of Nerve Cells and Thai. '^^^^ author in these two papers pre- 

 Processes. Arch. f. Anat. u. Physiol. Anat. sents the results of a Study of the finer 

 Abth. pp. 204-204; and Supplementband, ^ ^ . n 1 ..1 i- 



,^„ ^-/\,^..^oJ.. structure of nerve-cells bv the applica- 



PP- -73-305 > 109/ > . . " 



fion of various fixing reagents. As a 



result of his investigations, he concludes that the corpuscles of Nissl in nerve- 

 cells are not present in normal living cells, but first appear upon treatment with 

 acids, either formed by post-mortem changes or present in the fixing fluid. As 

 to the structure of the mass of the cell-body of nerve-cells, the author commits 

 himself to the alveolar theory of Biitschli. In the axis-cylinder the same structure 

 is present, the meshes prolonged in one direction, while the transverse walls are 

 very delicate and short, giving to the axis-cylinder the appearance of a longitud- 

 inal fibrillation, so often described as constituting the real structure. The alveolar 

 structure of the cell-body and the axis-cylinder process (neurite) was demonstra- 

 able by most of the methods, but unless a small cone of light and a less refrac- 

 tive mounting medium — such as water or glycerine — were employed, the transverse 

 connections were not apparent, and the appearance was of a true fibrillar struc- 

 ture. Of the fixing fluids tried, Van Gehuchten's alcohol-chloroform-formic acid 

 mixture were found to be most useful in the study of the structure of the axis- 

 cylinder. A double stain with erythrosin and methylen blue was largely 

 employed ; likewise, Heidenhain's iron ha^matoxylin. B. F. Kingsbury. 



,. , .J _ . ^, , ^ ^ In the Hensen method, a net of silk 



Kotoid, C. A. Some Important Sources of 



l':rror in the Plankton Method. Science, bolting cloth is drawn vertically 

 N. S. 6: No. 153. through the water, and the catch is 



multiplied by some factor, the coefficient of the catch, to determine the amount 

 of plankton in a given column of water. The coefficient, calculated by Hensen 

 for a series of velocities, is applied without regard to the character of the 

 plankton. Experiments show that the coefficient varies with the amount and 

 nature of the catch, the straining power of the net being affected by clogging in 

 the case of heavy planktons. The effect of progressive clogging is such that 

 from S4 per cent, to OC) per cent, of the catch is calculated to be taken in the 

 first fifteen meters of a thirty-meter haul. Hensen and others state that with 

 the finest bolting cloth only a few organisms can pass through the meshes, but 

 Kofoid finds that the struggles of the organisms and the pressure of the water 

 aid the escape of the planktonts, and that in the pumping method of collection 

 the net retains from 5 per cent, to less than 1 per cent, of the total number 

 of forms present, exclusive of bacteria. e. m. k. 



Biedl, A. Ueber das histologiche Verhalten The author Studied the peripheral and 



der peripheren Nerven und ihrer Centren central degeneration of nerves on rab- 

 nach der Durchscheidung. Wiener, khn. '^ 



Wochenschr. 10: No. 17, pp. 3S9-392. Ab- bits and dogs by resecting 1 to 1.5 cm. 



stractinZeit.f.wiss.Mikros. 15:3; 1897. pieces of the nerves. The dogs were 



killed quickly in chloroform, five, ten, and eighteen days afterwards, and the 



