48 BULLETIN OF THE BUSSEY INSTITUTION. 
divided into fractions and tested at once with a solution of phenyl- 
hydrazin acetate prepared by shaking together 1 cc. of phenyl- 
hydrazin, 2 cc. of glacial acetic acid, and 10 cc. of water. 
For the sake of gaining an approximate idea in each instance: 
of the quantity of mannose in the product of the hydrolysis, the 
phenylhydrazin reagent was applied methodically as follows: The 
neutralized liquor was divided into several fractions each of 1 cc. 
The first of these fractions remained undiluted, but to the second 
fraction 1 ec. of water was added, to the third fraction 2 cc. of 
water, to the fourth 3 cc., and so on, the series of dilutions being 
carried as far as was thought to be by any possibility necessary. 
To each of these fractions 12 drops of the aforesaid phenyl- 
hydrazin acetate reagent were added, the mixtures were left to 
stand during at least two hours, and the precipitates were 
examined under the microscope to see if they contained balls or 
crystals of mannose-hydrazone. In case none of this substance 
appeared at first, the precipitates were examined at intervals dur- 
ing forty-eight hours, and it was only after this long-continued 
scrutiny that the absence of mannose-hydrazone was admitted. 
By this method of testing — which was applied not only to the 
examination of pine wood but to all the other materials described 
in this article—it is easy to assure one’s self that some things 
contain much more mannan than do others. ‘Thus mannose- 
hydrazone was detected in ten successive fractions of the unevap- 
orated product of the hydrolysis of 10 grm. of clean buttons cut 
from the ivory nut (Phytelephas macrocarpa),— that is to say, 
mannose-hydrazone was found not only in the first undiluted 
fraction but in the nine following fractions in which 1 ce. por- 
tions of the product of the hydrolysis had been diluted respec- 
tively with 1, 2, 3, 4, 5, 6, 7, 8, and 9 cc. of water. But no 
mannose-hydrazone was detected in the liquor of the tenth 
dilution. In a similar way mannose-hydrazone was detected in 
the first five dilutions of the product of hydrolysis from 6 grm, 
of powdered date stones, but none appeared in the tests made 
with the sixth and subsequent dilutions. It will be noticed that 
the tests with ivory nut, date stones, and the flesh of cocoa nut 
(see below) refer only to unevaporated products of hydrolysis. 
In order that they may serve as standards of comparison, these 
results are printed below, under the table relating to pine wood. 
