Atkins — Oxydases and their Inhibitors in Plait t Tissues. 203 



reagent. It was noticed that the mucilage connecting the cells of the diatoms 

 Tabellaria and Pinnularia, epiphytic on Sphacellaria, also assumed a blue 

 colour rapidly. Furthermore, slime pressed from the couceptacles of Fucus 

 serratus gave this blue with benzidine and the peroxide. From their rapidity 

 it appears that these reactions are due to oxydases ; but the crucial test of 

 boiling was not made. The natural pigment of the diatoms rendered it 

 impossible to decide whether the benzidine reaction was produced inside the 

 valves also. Eecently Kylin (5) has obtained varieties of slime or mucilage 

 from both brown and red algse. All agree in remaining uneolouted by 

 zinc chloro-iodide, and in giving the pentose reactions with phloroglucin and 

 orcin, followed by hydrochloric acid in each ease. It seems likely that 

 oxydases are concerned in the production of these slimes, just as they 

 probably function in the production of sclerenchyma, as pointed out in 

 Part I of this series. From the fact that in many eases cellulose walls 

 are coloured blue by benzidine, it appears that oxydases are intimately 

 associated with many of the changes occurring in these so-called passive 

 portions of the cell. 



Some Reactions of Phceopliycean Extracts. 



Attempts were made to obtain active oxydase preparations from members 

 of this class by precipitating dilute alcoholic aqueous extracts with alcohol, 

 thus separating the enzyme from the soluble inhibitor, as was done in the 

 case of Iris germanica leaf extract (1). Both Pelvetia oanaliculata and 

 A&cophyllum nodosum were tested in this way, the latter being allowed to 

 soak for three days. The precipitate was washed well with spirit ; but when 

 water and the guaiacum reagent were added, no blue colour appeared, nor 

 did subsequent addition of hydrogen peroxide produce an alteration. Perhaps 

 the disintegration of the tissue was not sufficiently complete. Further 

 attempts are being made in this direction. 



The presence of an active reducing agent in these algse is shown by the 

 fact that a macerated Fucus serratus thallus yields a solution which almost 

 decolorizes dilute aqueous methylene blue, changing it to a light greenish 

 hue. The same almost colourless extract also destroys the guaiacum blue 

 produced by Hedera Helix, leaving a light green colour only. The filtrate 

 from the attempted enzyme extraction of Ascophyllum, which was of a 

 golden brown colour, was also found to destroy the colour of methylene 

 blue, for though producing but little effect when first added, a greenish colour 

 appeared on warming. These solutions were faintly acid; this was noted 

 because guaiacum blue is decolorized by alkalis. 



