182 BOTANICAL GAZETTE [AUGUST 
The most recent paper of the series? reports the results of an investigation 
of the generally accepted idea that an excess of basic lead acetate, when a 
to a solution of invert sugar, precipitates a portion or all of the levulose present 
as a soluble lead salt. This idea is shown to be incorrect; levulose’ in dilute 
chlorides, sulphates, or carbonates. If the acetate be added in excess and 
allowed to act upon the sugars for a considerable length of time, the amount of 
levulose present decreases progressively with increase in the time during which 
the lead is allowed to act. This is due to the formation from the levulose, not 
of a lead salt, but of a substance having a lower reducing power and much less 
optical activity than has levulose. It is suggested that this substance may be 
glutose, which was made by Lopry DE BRUYN and VAN EKENSTEIN by heating 
a 20 per cent levulose solution with lead hydroxide at 70-100°, and which was 
described by them as having about one-half the reducing power of dextrose 
as possessing only very slight optical activity. Davis considers that 
basic lead acetate acts at ordinary temperatures in the same way as does lead 
hydroxide, the action becoming more rapid as the temperature rises. 
n order to avoid any loss of levulose when clearing a solution, the basic 
lead acetate must be added little by little in the cold until precipitation of the 
impurities is just complete, care being taken that the excess employed is not 
greater than 1 cc. per 100 cc. of sugar solution (best accomplished by making 
preliminary tests upon small portions of the filtrate). The solution should at 
once be filtered through a Buchner funnel, washed, and the excess of lead 
immediately precipitated by the use of Na,CO, or Na,SO,. If excess of NazCOs 
be avoided and the solution be shaken up with a little toluene, it may be kept 
for months without the occurrence of any change. This treatment is very 
much to be preferred to the use of normal lead acetate, which fails to wholly 
remove optically active gums and which is a poor clarifying agent, but it is 
essential to accuracy that the precipitation be conducted in the cold. 
here reviewed were preliminary to a series on the formation 
and rentuiooktiok of carbohydrates in plants, to be reviewed later —JOsEPH S. 
CALDWELL. 
Taxonomic notes.—Arruur;’ in continuation of his studies of the Ure- 
dineae, has described 23 new North American species in the following genera: 
Uromyces (2), Puccinia (8), Aecidium (10), Uredo (3). _The majority of them 
are from Mexico and Central America 
Asue? has described a new Vaccinium (V. Margarettae) from the mountains 
of ee and South Carolina, where it occurs in association with V. vacillans. 
7 Dav: vis, Wrtt1AM A., The estimation of carbohydrates. V. The supposed pre- 
cipitation of reducing sugars by basic lead acetate. Jour. Agric. Sci. 8:7-15- 1910. 
§ ARTHUR, J. C., New species of Uredineae. X. Bull. Torr. Bot. Club 45:141- 
156, 1918. 
9 ASHE, W. W., Notes on southern woody plants. Torreya 18:71-74. 1918. 
