Gruenberg and Gies : Notes ox " bastard" logwood 375 



freshly prepared solution of the commercial " extract of logwood," 

 and a solution four weeks old that had faded to a straw-yellow. 



The chemical alterations undergone by the aqueous solution 

 of the commercial extract are accompanied by such a decided 

 change in color and in chemical properties that from a com- 

 parative study of such extracts we expected to learn something 

 definite regarding the actual differences between the pigments in 

 the heart- wood of " red " logwood and in that of the bastard 

 variety. We were unable, however, to do so. 



Experiments were started to determine, if possible, the relations 

 of light and of air to the discoloration of solutions of logwood 

 extracts. In a (gw weeks all the preparations had been attacked 

 by growths of Peniciliium, R/iirjopits and other fungi. After 

 filtration the solutions showed no appreciable differences in shade 

 or color. But on diluting these filtered solutions with two parts 

 of water and eventually with eight parts, differences were readily 

 observed. 



The solutions which had been in the light showed no change 

 in color, whereas those kept in the dark had become distinctly 

 yellow. The extracts to which the air had free access manifested 

 the greatest changes. 



Solid matter in logwood extracts. — We desired to ascer- 

 tain, in comparative determinations, the quantities of solid matter 

 in aqueous extracts of the various logwoods under investigation. 

 The absolute amount of solid substance in ioo c.c. of the extract 

 was always small — less than 0.02 gram. In the drying process 

 slight decomposition seemed to result and perfectly constant 

 weights could be obtained only after a long time. Although the 

 absolute changes in weight were only very small, the proportion- 

 ate variations in quantities so slight were quite large. For these 

 reasons no comparative observations were attempted in this con- 

 nection. The use of very large volumes of extract, to reduce the 

 comparative effects of the variations referred to, was impracticable. 



The general question of the physiology or chemistry of pig- 

 ment-formation in the heart-wood was not approached at all, nor 

 were the histological characters of the varieties compared. 



There can be no doubt that " bastard ' logwood is, as Prof. 

 Earle also concludes (see page 368) a distinct variety or subspecies 



