Journal of Applied Microscopy. 373 



Busch, Ch. K. Ueber eine Farbungs methode The well known disadvantage of 



secundarer Degeneration des Nervensystem Marchi's method is the poor penetra- 



mit Osmiumsaure. Neuro. Centralbl. 17: ^. . • -j • ^ ^.u j i „ 



lo p 476 i8q8 tion of osmic acid into the deeper layers 



of tissue. This can be avoided by mix- 

 ing the osmic acid in a solution of sodium iodide. The substance gives osmic 

 acid quicker penetration and fixing powers. A formol hardened preparation was 

 put into a mixture of : 



Osmic acid, .... 1.0 



Sodium iodide, . . . 3.0 



Distilled water, . . 300.0 

 allowed to remain for five to seven days, and passed through the alcohols to cel- 

 loiden. Sections have the same color as after Marchi's treatment, only the normal 

 tissue is brighter, and consequently the degenerating area stands out more clearly, 

 being visible to the naked eye. a. m. c. 



Marsson, Dr. Planktologische Mittheilungen. The results of five months' observation 

 Zeits. f. Angew. Miki-os.4: 169-174,1898. ^f ^j-^g plankton of the Leipsig ponds 



are given, with a table of the forms found. There was a pronounced variation 

 in the plant and animal constituents of the plankton, many organisms suddenly 

 appearing and then disappearing after a few days. Tintinidium fluviatile, an 

 organism living in a gelatinous tube, made its first appearance in one of the 

 ponds on the twentieth of May ; on the twenty-sixth it formed the largest 

 constituent of the plankton. Then it disappeared and did not return. A 

 closely related form, Codanella lacustris, appeared in this pond in April, then 

 disappeared entirely and was first found in other ponds in August. Two other 

 ponds, separated only by a road, never contained the same forms. While the 

 one on the south contained quantities of Volvox aureus, not a single specimen 

 could be found in the one on the north. In September Synura uvella appeared 

 here in large numbers, while there were none at all in the other. Both ponds 

 afforded similar conditions of depth, character of soil, light, and plant growth. 

 Swans frequently went from one to the other, and they were visited by other 

 water birds. E. M. Brace. 



„..,„,„ - -, , cft X- Dr. L. C. Bristol gives a gold chloride 



Bristol, Dr. L. C. Jour. Morph., 50: No. i. . 



method which he has found to give 



very delicate results in the study of the nervous system. He recommends it for 



vertebrate or invertebrate, adult or larval tissue, although there must be special 



adaptations determined by experiment for each tissue. Formic acid is the 



variable factor and its action depends upon time and strength. The material is 



killed in a 10 per cent, or 1-5 per cent, solution of formic acid, where it is left 



for five or ten minutes. Without washing, place in a 1 per cent, solution of gold 



chloride for twenty-five minutes ; change, without washing, to a large volume of 



10 per cent, formic acid and leave twelve to eighteen hours, or until reduction 



occurs. Small pieces, not thicker than 5 mm., should be used. Maceration 



may be avoided by reducing the strength of the acid and the time of action. 



During reduction the preparation may or may not be left in the sunshine. After 



reduction pass the tissues through the alcohols to chloroform and imbed as soon 



as possible. Sections should be about 18 ,1 thick. E. M. Brace. 



