164 
THE ENERGY OF THE LIVING PROTOPLASM. 
specific chemical work, and others again are adapted to functions 
of propagation, while in the animal kingdom special organs for 
visible motion and for sensation are developed. The “ chemical 
factories in the service of an organism,” the glands, of simple 
structure in plants, but forming complicated organs in the 
higher animals, betray again a far-reaching differentiation. 
They may secrete enzymes, carbohydrates, different acids, fat, 
or wax. Products secreted by vegetal cells alone are terpenes 
and resins. (r) Glands secreting poisonous compounds (tox- 
albumins ; carbylamines (?)) occur in the mouth of snakes, in the 
skin of the toad, on the feet of scolopendras. Crustaceans and 
beetles produce chitin, spiders and caterpillars fibroin. Carabidæ 
secrete butyric, bees and ants formic acid. Especial interest is 
connected with the anal glands of the skunk, 1 (2) musk deer, 
beaver, and civet. Again, the livers of different animals vary 
in their actions, as must be inferred from the composition 
of bile and urine. Dogs can produce ethyl sulphide {Abel) 
and an oxyquinoline-carboxylic acid (. Kretschy ), birds ornithuric 
acid; (3) the bile of geese contains chenotaurocholic, that of 
swine hyotaurocholic acid. Birds and snakes produce more 
uric acid than urea, while the reverse is the case in mam- * 
malia. The products of metabolism exhibit, thus, considerable 
discrepancies. (4) 
This very brief survey may bear sufficient testimony to the 
variety of the chemical work of organisms, and to the special 
adaptation of the plasmic energy to the most varied chemical 
performances. Few authors have thus far tried to propound an 
(1) An elaborate treatise on the resin-producing glands of the conifers was 
recently published by H. Mayr , formerly professor in the Imperial University of 
Japan. 
(2) The yellow liquid secreted by the skunk-glands and ejected in self-defence is 
a primitive and effective weapon, having a most repulsive odour. It contains 16 per 
cent of sulphur (Szvarts), and is probably a mixture of several mercaptans with one 
or more nitrogenous compounds. 
(3) This acid, a dibenzoyl-ornithin, is secreted after introduction of benzoic acid; 
ornithin again is probably a diamido-valerianic acid [Jaffé). 
(4) Also, pathological processes may be caused by administration of certain 
compounds only in certain animals ; thus phloridzin will produce diabetes in dogs, 
but not in rabbits or frogs. 
