[Vol. 6 



84 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



substances present in the fungous flour. Hence I think we 

 may conclude that there is no deamination of ty rosin by 

 enzymes in Armillaria mellea and Daedalea confragosa. 



Fate of the carboxyl and phenol groups. — Chodat and his 

 students, as well as Folpmers, have studied the relations of 

 the carboxyl group to a certain extent. They have concluded 

 that the carboxyl is destroyed, carbon dioxide being evolved, 

 and that the carbon atom next the carboxyl group forms an 

 aldehyde group which may be further oxidized to a carboxyl, 

 or to one alcohol and one carboxyl group by two aldehyde 

 groups uniting with a molecule of water. On the animal side, 

 the product of the reaction is commonly reported in the 

 text-books as due to the formation of homogentisic acid, with 

 the intermediate formation of a quinoid structure and the 

 shifting of the phenol group on the ring. This gives an 

 adequate explanation for the presence of color in the com- 

 pound, but is gradually being considered untenable. Dakin 

 ('10, '10% 11, 12) thinks that his theory of ^-oxidation will 

 fit the case in the normal metabolism of tyrosin, where it is 

 completely oxidized, and that homogentisic acid formation 

 which is said to occur in alkaptonuria is one of those peculiar 

 anomalies of metabolism which sometimes take place. For 

 recent work from the animal side, see also papers by From- 

 herz and Hermanns ('14) and Kotake ('18). 



If the P H values are plotted on a logarithmic scale and the 

 number of cubic centimeters of standard acid or alkali neces- 

 sary to bring the original solution to each successive step in 

 hydrogen ion concentration are plotted on the millimeter 

 scale, we obtain a graph which enables us to ascertain sev- 

 eral important facts, bearing in mind that absolute values 

 are obtainable only when a single pair of substances are re- 

 acting in such a way that the hydrogen ion concentration is 

 affected. It is a well-known fact, however, that the stronger 

 alkali or acid will inhibit the dissociation of the weaker so 

 that it will not react readily in the presence of the stronger. 

 Hence if the hydrogen ion concentration values do not lie 

 too close together, it is often possible to determine the 

 amounts of two or more acids or bases in the same solution. 



