TO 
blue; but those of fruit-tubers and matured foliage are stained brown. 
The "first is of the amylaceous, the second of the woody type. The: 
larger proportion of the cellulose structure of the nutritious fruits, foli- 
age, and grasses, is easily converted into starch and ultimately into. 
sugar, by chemical means, and by animals when used as food, and are 
known as carbohydrates. The mycelium of mycroscopic fungi consists,. 
for the most part, of cellulose, and although the fungi are very low 
forms of plant- life, they are not only the principal formers of some of 
the organic acids, as the acetic, but they grow to maturity in them ;: 
while the woody cellulose of the higher plants dissolves in the acetic: 
ferments and becomes food for the cryptogams. Some varieties of myce- 
lium take the blue stain by iodine and sulphuric acid, while other kinds. 
are turned of an amber-color by the same tests. 
When gun-cotton, a nitro-cellulose body, is treated very frequently 
with the iodine and acid tests, as described in the experiments with 
cotton and flax, it becomes yellow or amber-colored ; and when the fine 
saw-dust of box-wood is similarly treated, it appears, when viewed 
under the microscope, of three colors, amber, green, and blue; but the 
latter color appears in very small quantities. Chitine, the cellulose of 
insects, is stained yellow, and is supposed by some chemists to be 
combined with nitrogen. Color cannot be relied on wholly as a test for 
cellulose, since it assumes so many colors under treatment with iodine 
and acid. The following colors are frequently observed when treating 
cellulose and starch with iodine and ‘sulphuric acid: Purple, bluish- 
purple, green, yellow, amber, reddish-amber, pale-blue, deep-blue, and a 
translucent amylaceous white, When starch is acted on by sulphuric 
acid alone it dissolves and is partially carbonized. 
In making investigations on animal tissues, viscera and blood, I have 
endeavored ‘to ascertain the condition of the cellulose in them, whether 
it is tubular, membraneous, or amorphous. If a portion of brain is. 
bruised and combined with iodine and the acids mentioned, so as to 
produce the boiling heat, amber, purple, and blue colored forms are- 
frequently seen, particularly so when the brain of a herring is used in 
the experiment. Angular plates are always seen in the brain of the calf, 
and are without color. until subjected to the action of iodine and suita- 
ble acids, when they become blue. These plates have been by some 
writers termed cholesterine, but there is no chemical authority that I can 
find which declares that cholesterine is turned blue by the cellulose and 
starch tests. In my experiments on the heart, liver, muscles, &c., of 
the higher animals, I never fail to detect structural cellulose in them. 
8, 9, and 10 represent some of the forms found under chemical action ; 
i, Fig. 2 2, is similar; 2 and 3 and the other form of this plate are pro- 
duced from 1 by using extra acid, and sometimes by slight friction. In 
animal tissues and viscera a great variety of cellulose and tubular forms 
may be detected in various stages of color, which are not represented by 
the cuts. To be successful in these experiments a great deal of perse- 
verance is necessary, aS the animal cellulose is well protected by the 
other substances present, which frequently resist the tests applied until 
they are repeated several times. Fresh animal tissues, viscera, &c., 
should be used in making preliminary examinations. 
Since writing the foregoing, 1 have made some new experiments on 
human arterial blood taken directly from. an artery, and also on the 
mixed blood of a fowl. In each case well-defined amylaceous matter 
has been detected. 
The fresh blood of a fowl was whisked with a fork to separate the 
fibrine from the liquid portion. The fibrine was next dissolved in dilute 
