DIGESTION OF AMYLACEOUS SUBSTANCES. 417 
and states that “ whatever may be the species of vegetable 
which has produced it, the feculent seed is a small, full body, 
formed of concentric superposed layers ; and these layers are 
formed of extremely small granules united in a membranous 
form.” He then asks — 
“ But what is the matter which unites these granules F To reply to 
this question, I must first make one general remark ; it is that as the grain 
of fecula is a veritable organ, that is a living particle, it must contain some 
portion of nitrogenous matter; for, as has been well said, the presence 
of nitrogenous principles is as indispensable to the manifestation of 
life in plants as in animals. Experiment likewise proves distinctly, that all 
feculent grains contain nitrogen. To ascertain this, it is sufficient to place 
in a small glass tube closed at one end, a few centigrammes of any kind of 
fecula and a small piece of caustic potassa; then put into the upper part of 
the tube with the proper precautions, a small piece of reddened litmus 
paper, above which place a little cotton wool to delay the passing off of the 
gas, and on heating the tube with a spirit lamp so as to destroy the organic 
matter, the ammoniacal vapours which rise will immediately restore the blue 
colour of the test paper. 
“ M. Jacquelaiii considers that the matter in question is albuminous, but 
several circumstances lead me to think that it is gelatinous. But as 
far as our present investigation is concerned, this difference of opinion 
is unimportant. There is another peculiarity to which I wish to call 
attention. 
“ Iodme is known to be the re-agent, by means of which we can best 
ascertain the presence of the smallest traces of fecula wherever they may be. 
Now, I am of opinion, that the property of assuming a blue colour does not 
belong to the amylaceous substance, properly so called, or granules ; but 
rather to the almost imperceptible trace of nitrogenous matter which 
envelopes and unites them. 
“Eor the granules to disappear and become soluble they must be meta- 
morphosed into glucose or dextrine, which may be effected under various 
influences which cannot intervene in the digestive process. There is, how- 
ever, one winch is an exception, I mean the saccharification of the fecula 
produced by the influence of certain nitrogenous matters, such as the saliva, 
the pancreatic juice, some kinds of mucus, the serum of the blood, &c., 
experiment having shown that these matters which have no action upon 
the fecula when not hydrated, may, in certain cases, convert a certain 
quantity of starch paste into sugar and dextrine. I must, however, 
observe, that even under the most favorable circumstances, only a very 
small proportion of matter undergoes this transformation, and that 
for this purpose, a neutral or alkaline reaction is a sine qua non , in 
condition which the digestive tube seldom fulfils, as I am about to show.” 
In the second part, M. Blondlot examines the theory of the 
conversion of amylaceous matters into sugar during the 
process of digestion, and observes that, according to several _ 
distinguished physiologists, aliments should be arranged in 
three distinct classes, namely : 1st, Albuminous substances, 
whose digestion is effected by the gastric juice ; 2d, Fatty 
matters, which are formed into an emulsion by the bile and 
the pancreatic juice ; 3d, Amylaceous substances digested 
by the saliva, either with or without the aid of the pancreatic 
