SYNTHETIC WORK IN CARBOHYDRATES 337 
means of their hydrazones and osazones. 1 ” However, with the 
exception of mannose, the hydrazones of other sugars are mostly 
soluble in water. Hence, the reaction with phenylhydrazine 
is carried on to a further state, which results in the formation 
of the insoluble osazones. These compounds differ decidedly 
in color and system of crystallization. They have sharp melt¬ 
ing-points, which lead to their easy identification. 
Another class of substances, which are called mercaptals, 
and are compounds of sugar with sulphur, of the composition 
CH 2 OH(CHOH) 4 CH(S 2 C 5 H) 2 , furnishes a means of separat¬ 
ing and distinguishing the aldehyde sugar compounds. 
The synthetical sugars containing 7, 8, and 9 carbon atoms, 
derived from the groups containing less carbon atoms, may 
be made by Kiliani’s method. 
It is an interesting fact that the sugars containing 3, 6, and 
9 atoms of carbon are fermentable; while those containing 
4, 5, and 7 atoms of carbon cannot be fermented. 
Fischer has suggested wherein the interest of these massive 
sugar molecules lies. It is in physiological research. He has 
proposed, as worthy of attention, that these higher synthetical 
sugars be experimented with as to their full physiological value. 
Possibly the tissues of animals nourished with these higher 
sugars may yield other chemical products; the liver may give 
a new glycogen, and a new acid may be found in the milk secre¬ 
tions from the mammary glands. Here may possibly be opened 
a new research ground for the biologist. 
The pentosans are compounds belonging to the sugars 
containing 5 carbon atoms. These pentosans occur in various 
parts of plants of different age and development. The amount 
increases during the development of the plants. The wood 
of dicotyledonous plants is richer in pentosans than that of the 
Coniferae. It is thought by De Chalmot that these substances 
are reserve materials. But they seem of importance in the 
formation of wood, for they are developed at this stage. 
Arabinose is one of the important members of the pentose 
series. It was discovered by Scheibler on boiling the gum of 
the cherry tree with sulphuric acid. This compound was con- 
1 The reaction and products of some of these sugars were demonstrated. 
