522 SUMMARY OF CURRENT RESEARCHES RELATING TO 



BOTANY. 



A. GENERAL, including Embryology and Histology of the 

 Phanerogamia. 



Chemical Difference between Dead and Living Protoplasm. — Dr. 

 0. Loew sends us a photograph illustrating his researches on this 

 subject,* from which Fig. 90 is copied. 



The upper part of the woodcut shows a filament of Spirogyra 

 nitida Ktz., hilled by a O'l per cent, solution of citric acid before 



Fig. 90. 



treatment with the silver reagent, no blackening being produced, 

 and the spiral arrangement of the chlorophyll-bands being distinct. 

 The lower part shows a filament when placed in the living condition 

 into the silver reagent, the reducing effect of the living protoplasm 

 on the silver-salt having converted the cell-contents into a black 

 opaque mass. 



Killing of Protoplasm by Various Reagents.t — Loew and 

 Bokorny have applied their test for distinguishing between dead and 

 living protoplasm, viz. its power of reducing dilute alkaline silver 

 solutions, to determine the degree of resistance offered by protoplasm 

 to various destructive agents. After complete withdrawal of light 

 for five days, about 50 per cent, of the filaments of several species of 

 Spirogyra still showed signs of life ; it was not till the sixteenth day 

 that all were completely killed. Twelve hours' desiccation over con- 

 centrated sulphuric acid destroyed the appearance of life in almost 

 every cell. Triturating in a mortar destroyed life, even where there 

 was no apparent injury. After warming in water of 46° C. for a 

 short time, about 10 per cent, of the cells still showed signs of life, at 

 55° about 2 per cent. ; and a temperature of 60° altogether destroyed 

 life. Exposure of one hour to vapour of ether destroyed life except 

 in some cells containing a large amount of oil and in spores, sugar 

 being formed during the process. After twelve hours in chloroform- 

 water, 5 per cent, of the cells were alive ; two days in petroleum 



* See this Journal, i. (1881) p. 906; ante, p. 67, 361, and 440. 

 t Pfliiger's Arch. f. d. gesammt. Physiol., xxvi. (1881) pp. 50-9. See Bot. 

 Centralbl., ix. (1882) p. 392. 



