244 BOTANICAL MICROTECHNIQUE. 







21. The Loew-Bokorny Reagent for "Active Albumen." 



445. Loew and Bokorny (cf. I and II) have, in various 

 papers, maintained the view that living and dead proto- 

 plasm differ from each other in that only the former h:is 

 the power to precipitate silver from an alkaline silver- 

 solution. These authors conclude from this that living 

 albumen contains aldehyde groups which at once undergo 

 a breaking up, at its death. [They have observed a pre- 

 cipitation, in living cells treated with a ,\% solution of 

 coffein, of abundant small granules which they believe to 

 consist of " active albumen," and term "proteosomes."] 



446. It has, however, been shown by various authors (cf. 

 especially Pfeffer VII) that the observations of Loew and 

 Bokorny are partly incorrect and that the bodies called by 

 them " active albumen " certainly consist in part of tannin 

 and similar substances. But, since the Loew-Bokorny 

 " Life-reagent " has already been used by other investigators 

 for the recognition of living albumen, and may perhaps be 

 capable of furnishing a basis for some conclusions concern- 

 ing the contents of the cell, when more critically employed, 

 the methods used by these investigators may be briefly out- 

 lined here. 



447. The silver reagent called by Loew and Bokorny 

 " Solution A M is prepared by mixing 13 ccm. of caustic 

 potash solution of specific gravity 1.33 (containing 33^ of 

 KOH) and 10 ccm. of aqua ammonia of specific gravity .96 

 (containing 9$ of NH 3 ) and diluting the mixture to 100 

 ccm. For use, I ccm. of this solution is mixed with I ccm. 

 of a \<f> silver nitrate solution, and the mixture is diluted 

 to one liter (1000 ccm.). 



448. The "SolutionB" is prepared by adding 5 to 10 ccm. 

 of a saturated solution of lime to a liter of a T -gVo$ solution 

 of silver nitrate. 



Both solutions must be used in large quantities on account 

 of their extreme dilution, and but a small number of the 

 objects used should be placed in them. The deposition of 

 silver usually begins only after some hours, and it is gen- 



