MODERN STEPS OF PROGRESS. 



9 



of lime, and concludes, that this belongs to the molecular system 

 of this organism and contributes to its vitality ! But if all the 

 substances found in protoplasm participated in the first cause 

 of life, then all excretionary substances that remain previous to 

 their expulsion for a certain time in the protoplasm, further the 

 sugar formed from starch and converted the next moment into 

 cellulose, the hydrocarbons, aldehydes and esters produced to 

 attract insects for fecundation of the flowers, the wax secreted to 

 form a film upon the epidermis of leaves, the urea and uric acid 

 produced in animals from proteids : all these substances would be 

 parts of protoplasm and would participate in the cause of vital 

 functions. All these combinations are formed in the protoplasm 

 of different cells and must exist there even if only for a short 

 time. This old view of declaring everything found in pro- 

 toplasm to be an essential part of the protoplasm, and attribut- 

 ing to it even vital actions leads simply to absurdities ! — 



Hanstcin defined protoplasm " as a semiliquid substance 

 consisting of proteids, insoluble in water, generally of neutral 

 reaction, transparent and refracting the light a little more than 

 water." This definition however is not perfect ; we miss the 

 chemical side of the question, above all the distinction between 

 living and dead protoplasm. The first, who treated this problem 

 scientifically, was E. Pfliiger 1 ) in the year 1875. He started 

 from the chemical fact that the living cells take up oxygen, 

 while the dead do not. From this fundamental difference the 

 conclusion is justified, that the albuminous substance of the 

 living protoplasm has another chemical character than that of the 

 dead protoplasm. In other words : the living protoplasm is ex- 

 ceedingly liable to chemical change, and if that change takes 

 place, death results. Pfliigcr pointed out also, that the decom- 

 position of albuminous matter in the living animal organism 

 yields other products that the decompositions artificially accom- 

 plished in the laboratory and concluded, that the nitrogen of the 

 "living albumen" is linked in a different manner to other 

 atoms. 2 ) He supposed that the cyanogen-group is this form, 



1) Pfliig. Arch. Vol. 10. 



2) This conclusion is however not justified ; the same albuminous matter can 

 yield under different conditions very different products. The albumen, which is 

 oxydised in the living body is certainly for the greater part circulating dead albumen 

 and not living protoplasm. The latter brings on the oxydation of the former. 



