190 REPORT OF THE COMMISSIONER OF AGRICULTURE. 
mula as a pure body, and called the fiber which had been obtained by 
extraction of wood by these neutral solvents and acetie acid glycolignose. 
Thomsen considers all previous experiments to have failed hitherto 
because of using too powerful reagents for extraction, whereby the sub- 
stances treated suffered partial decomposition. 
He treated birch wood with soda lye at common temperatures, and 
easily extracted a substance which was reprecipitated by dilute acids. 
Pine wood, on the other hand, contained almost none of this substance. 
Poumerede and Figuier, in 1847 (Jour. Pharm., 12, 81; Jour. fiir Prak. 
Chem., 42, 25; Annalen, 64, 387), are the only persons who have pur- 
sued this investigation, and they obtained. from poplar and beech, by 
such treatment, a substance free from nitrogen, and having the composi- 
tion of cellulose, and possessing, as they said, the properties of pectin or 
pectic acid. 
Now, this “ pectin substance” is what Thomsen has investigated, and 
he finds it to be isomeric with cellulose. He finds this substance to be 
most abundant in the birch and ash; then alder, vherry, oak, pear, beech, 
elm, willow, horsechestnut, and maple; while almost none was found in 
the pine, the amount varying from 20 per cent. in birch to less than 1 
per cent. in pine. It oceurs more abundantly in heart-wood than in the 
exterior of the tree. According to his method of preparation it is a 
white powder, insoluble in water at ordinary temperatures, but upon 
boiling it with a large quantity of water it gives a clear solution, which 
becomes opalescent upon cooling, but clears up upon addition of sodium 
hydrate. Its solution has an acid reaction, and upon evaporation it 
leaves a transparent, gum-like mass. He proposes to call this substance 
wood gum—* Holzgummi.” 
It appears, then, not improbable that between the extremes of starch 
and the sugars upon the one hand, and pure cellulose upon the other, 
there may exist many intermediate links in the condition of compounds 
isomeric with the one or the other, and readily passing in the processes 
of vegetable life from one form to ancther—compounds which have hith- 
erto escaped searching investigation, and which may indeed defy any 
attempts at their isolation, but which, nevertheless, may not be safely 
ignored in our estimations as to the nutritive value of the different 
grasses. 
tt certainly seems somewhat remarkable that so little has been done 
since those experiments of Poumerede and Viguier to either confirm or 
overthrow their conclusions. 
After treating the grasses with dilute sulphuric acid, as has been de 
scribed in the determination of the so-called amylaceous celiulose, the 
grass was boiled for two hours with a 2 per cent. solution of sodic hy- 
drate. This treatment removed considerable matter, part of which 
could be precipitated by excess of sulphuric or hydrochloric acid. This 
flocculent precipitate was dark colorecd, and undoubtedly contained a 
part of the albuminoids ef the grass; but the greater portion had the 
physical appearances and sclubilities of the humous substances of the older 
authors, or the wood gum, “ Holzgummi,” of Thomsen. Aswill be seen in 
the analyses of the several grasses and in the proximate analyses of vari- 
ous vegetable products in this report, this substance invariably appears. 
Jt is not improbable that it adds greatly to the food value of the plant; 
but whether it is originally present in the plant, or is a decomposition 
product formed by action of dilute acids and alkalies upon cellulose, 
seems not to be definitely settled. 
Regarding Thomsen’s Holzgummi from beech wood as a definite sub- 
stance, and taking into consideration the fact that from our alkali ex- 
