Plant oxydases and the chemical interrelationships of colour-varieties. 463 



among" themselves; flowers of tlie tall perennial Delphinium spp. give 

 a direct action whereas only an indirect action can be obtained from 

 flowers of the annual D. consolida. 



In some cases where neither reaction can be detected, it is 

 hig-hly probable that there is a suppression of the oxydase activity 

 through the simultaneous presence of bodies of a strongly reducing 

 nature. In confirmation of this suggestion Hunger^) has shown 

 that cocoa-nut milk from young nuts gives no blueing with guaiacum 

 owing to the interference of sugars present. The older nuts, in which 

 the sugars have been replaced by fats, give a strong oxydase reaction. 

 The same kind of observation is recorded by Aso^) of the Kaki-fruit: 

 here the suppression of the guaiacum reaction arises from presence 

 of tannin; when the tannin is removed by treatment with alcohol, 

 the oxydase can readily be detected. 



In all pi'obability, some such inhibiting body is responsible for 

 the non-appearance in many plants of the oxydase reaction though 

 that of the Peroxydase maj^ be given. C hod at and Bach suggest 

 that inability to give a direct guaiacum reaction, is due in many 

 instances rather to the present of powerful reducing substances which 

 deoxidise the peroxide than to the absence of part of the oxidising 

 mechanism. 



Autolysis. 



A certain interdependence has been found to exist between the 

 ettects produced by autolysis^) and the presence of oxydase activity. 

 When plants are submitted to autolysis in an atmosphere of chloro- 

 form vapour, changes in colour usually result within half an hour or 

 so of immersion. These changes may be described as follows: 



A. The whole plant, including the flowers, becomes brown. When 

 the flowers are pigmented with anthocyanin, the latter is destroyed 

 and replaced by the brown colouration. 



B. The colour of the flowers only is changed. Purple anthocyanin 

 becomes bluer or entirely blue; red anthocyanin sometimes slightly 

 bluer whereas blue anthocj^anin remains unaltered. 



'j Über die reduzierenden Körper der Ox3'dase- und Peroxydasereaktiou. Ber. 

 d. d. bot. Gesell., Bd. XIX. 1901. 



^) A physiological Funktion of oxydase in Kaki-fruit. The Bot. Mag. Tokyo, 

 1890, Vol. XIV No. 166. 



^) In animal physiology the term autolysis is used to mean self-digestion. In 

 this paper I am following the usage of several botanists in employing the term to 

 denote the changes vi'hich follow death produced by vapour of chloroform, toluol, etc. 



