26 THE ROYAL SOCIETY OP^ CANADA 



Further experimentation has been carried out with mucilage 

 extracted from dried material of Opuntia Blakeana obtained at Tucson 

 (on the domain of the Desert Botanical Laboratory). The material 

 was ground in a mill and sifted to remove coarser bits of tissue. It was 

 then allowed to stand in water till the mucilage had swelled to a highly 

 viscid mass. The supernatant water, which was somewhat brownish, 

 was poured off, and distilled water added. When sufficiently swelled, 

 the whole was strained through cloth to remove the bagasse. This 

 extract forms a culture medium for bacteria or yeasts, some of which 

 attack the mucilage, as is evidenced in time by the gradual lowering of 

 viscosity,^ accompanied by odour, probably due to protein breakdown. 



With a given preparation as above made it was found that when 

 5 cc. of mucilage was mixed with 10 mg. of dye, the following occurred. 

 Eosin and cerise did not affect the viscosity, Congo red, vesuvin, 

 neutral red and methylene blue, on the other hand, did so. It was also 

 observed that Congo red and vesuvin especially caused a marked 

 increase in turbidity, which is present in less degree in the original 

 extract, while in the neutral red preparation an initial turbidity was 

 soon followed by the formation of a clot, leaving the greater volume 

 of the fluid quite limpid. Of the dyes which appeared non-effective, 

 eosin produced no alteration in optical properties, even after 23 days, 

 whereas cerise produced some increase in turbidity. Ultramicroscopic 

 examination revealed the presence of suspensoids and flocks of coagu- 

 lum in the preparations with cerise, vesuvin, methylene blue and Congo 

 red. The coagulum in the neutral red showed its origin to have been 

 from similar suspensoids, the surrounding fluid being optically empty. 



Extracts were prepared of Linum mucilage (from the seed in- 

 tegument) and of Opuntia, and these, when ready for use, had approx- 

 imately similar viscidities and opalescence. A parallel series was set 

 up of these two mucilages. Each member of the series consisted of 

 10 cc. of mucilage to which 50 mg. of stain was added. The dry weight 

 of the Linum mucilage was 33 mg. per 10 cc, of Opuntia 70 mg. per 

 10 cc. After 12 days no change was observable in either mucilage 

 treated with methyl orange, fuchsin and eosin. Methyl orange dis- 

 solved only very slightly and lay on the bottom of the vial even after 

 many shakings. Fuchsin dissolved finally, but only very slowly. 

 Eosin dissolved quickly, but an amount of stain remained undissolved. 

 ' When the mucilage was decanted off and water was added to the 

 undissolved dye, it went into solution to a much higher concentration 

 than that in the original preparation, from which it would seem that 

 the presence of the emulsoid interferes with the solution of these dyes. 



8 Spoehr {I.e.) did not succeed in observing yeast fermentation to occur. 



