146 BOTANICAL GAZETTE [FEBRUARY 
of the extracts is not evident. It is true that the viscosity of the 
algal extracts greatly exceeded that of the commercial diastase 
and that action was very much more rapid in the latter than in the 
former; but this may have been due to some other factor, for 
although the extract from Polysiphonia was quite noticeably more 
viscous than that from Ceramium, yet the former completed diges- 
tion in two-thirds of the time required by the latter. Here, as 
before, we cannot draw definite conclusion, for there may have 
been a marked variation in purity between the two extracts. In 
some of the higher plants we find diastases that work very slowly, 
and it is not impossible that the algal diastases are also of this 
nature. It is a well known fact that by the addition of very small 
amounts of such substances as free mineral acids, neutral phos- 
phoric acid compounds, salts of aluminium, and asparagin salts, 
the amylolytic action of the diastase from higher plants is very 
much accelerated, and it might be mentioned here that small 
amounts of aluminium acetate and sodium.-chloride had the same 
accelerating effect upon the algal extracts. 
The Van Tieghem tests were of interest not only because they 
corroborated the macrochemical tests, but also because they showed 
that the manner of attack of the algal extracts was such that the 
starch grains were corroded. This would indicate that at least 
the most active enzyme present was a translocation rather than 4 
secretion diastase. 
The contrast between the colors of the precipitates of the differ- 
ent mediums tested with Fehling’s solution was very marked. 
The precipitates in the tubes containing the paste treated with 
algal extract was of the usual “‘brick-red”’ color. Paste treated 
with commercial diastase gave a light yellow precipitate, eve? 
though the tubes were allowed to stand for a considerable length 
of time before the test was made. This would indicate the presence 
of some colloid which prevented the deposit of free copper oxide. 
The precipitate in the tubes containing the algal extract showed 
that whether or not the viscous nature of the extract retarded amy- 
lolytic action, there were no colloids or other substances present 
which prevented a free deposit of the copper oxide. 
