258 SCIENCE PROGRESS. 



Yoshida, as he finds it still active after heating it to 

 7°° C. (5). 



Bertrand has sought for laccase with some success in 

 other plants and has indicated a rather wide distribution for 

 it (6). In his researches he has employed the guaiacum 

 test and appears to a certain extent to rely upon this 

 method of recognition. This is unfortunate, as most 

 investigators do not find it give entirely satisfactory 

 results. He says that an alcoholic tincture of gum guaia- 

 cum turns blue in the presence of air and a little laccase ; 

 if much of the latter is present, it turns from blue to green 

 and subsequently to yellow. In most cases however he 

 has confirmed his results by isolating the enzyme and 

 proving its presence by its action. This is really the only 

 satisfactory method of proving its existence. By the two 

 methods conjointly he has found laccase in the roots of the 

 beet, carrot and turnip ; in the tubers of the potato and 

 the Jerusalem artichoke; in the tuberous roots of dahlia; 

 in certain rhizomes ; in the fruits of the apple, pear, quince 

 and chestnut ; in the vegetative parts of lucerne, clover, 

 ryeg-rass and asparagus ; and in the flowers of Gardenia. 

 It may be prepared from these by extraction with water 

 and precipitation of the extract with alcohol. If the tissue 

 is green the extract may be saturated with chloroform and 

 allowed to stand for twenty-four hours, after which the 

 precipitation by alcohol may be carried out. 



Rey-Pailharde has found laccase in germinating seeds, 

 especially of plants of the Leguminosse (7). 



The activity of laccase appears to be associated in some 

 way with the presence of manganese. Its ash always con- 

 tains traces of an oxide of this metal, sometimes as much as 

 2 per cent. Bertrand (8) states that the activity of a pre- 

 paration of the enzyme is proportional to its content of 

 manganese. 



When prepared from lucerne it is poor in this constitu- 

 ent, and the effect of the addition of a salt of the metal can 

 be easily studied. Bertrand describes a typical experiment 

 on this point. He gathered several kilograms of lucerne at 

 the time of flowering, and bruised them in a mortar, pressing 



