MODERN ASPECTS OF THE LIFE-QUESTION. 76$ 



insects, but they secrete a gastric juice which digests them. Niigeli 

 has shown the presence of pepsin in yeast-cells, and attention has late- 

 ly been called by Wurtz and others to the juice of the Carica papaya, 

 which contains a pepsin-like substance capable of peptonizing fibrine 

 completely. Moreover, there is the closest similarity between dias- 

 tase and ptyaline ; and the milk of the cow-tree, recently examined by 

 Boussingault and found to resemble cream closely in composition, 

 shows the presence of an emulsifying agent in the vegetable kingdom 

 analogous to pancreatine in the animal. 



Another most curious proof of the identity of animal and vegetable 

 protoplasm has been given by Claude Bernard, who has shown that 

 both are alike sensitive to the influence of anaesthetics. A sensitive 

 plant exposed to ether no longer closed its leaflets when touched. As- 

 similation and growth, as well as germination, are arrested by chloro- 

 form. The yeast-plant when etherized no longer decomposes sugar to 

 produce alcohol and carbon dioxide ; while the inversive and non- vital 

 ferment still acts to convert the cane-sugar into glucose ; precisely as 

 under these circumstances the diastasic ferment converts the starch of 

 the seed into sugar. By arresting anaesthetically the process by which 

 carbon dioxide is absorbed and oxygen evolved, the true respiratory pro- 

 cess, being less affected, now appears ; and Schiitzenberger has proved 

 that the fresh cells of the yeast-plant breathe like an aquatic animal. 



It would seem, then, that the protoplasmic life of animals is iden- 

 tical with that of plants ; a certain measure of destructive metamor- 

 phosis taking place in each, evolving energy and producing carbon 

 dioxide and water. When, however, this function is examined quan- 

 titatively, its maximum is seen to be reached in the animal. While 

 the assimilative function characterizes the plant, the destructive func- 

 tion distinguishes the animal. Hence it is the function of the plant to 

 store up energy to produce the highly complex protoplasm. This, 

 consumed by the animal as his food, continues his existence as a living 

 being, the energy gradually set free by its successive steps of retro- 

 gressive metamorphosis appearing as the work which he performs. If 

 this view be correct, it would follow that every individual substance 

 found in the animal save only those which result from degradation 

 must be found in the plant upon which it feeds, and this is the fact. 

 The myosine which Kuhne has shown to be the distinctive proteid of 

 muscle, Vines has found in the aleuron-grains of the lupine and the 

 castor-oil plant, along with vitelline, the special proteid of the vitellus. 

 The researches of Weyl and Bischoff have proved that gluten is 

 formed in the dough of wheat-flour by the action of a ferment upon 

 the globuline-substance or plant-myosine which it contains, precisely as 

 Hammarsten has shown fibrine is produced in the action of a similar 

 ferment upon fibrinogen. Not only this ; Hoppe-Seyler has extracted 

 from maize the identical substance which has been shown by Liebreich 

 to be the essential chemical constituent of nerve-tissue, protagon. 



