266 BIOLOGY AND ITS MAKERS 
evident. Professor Joubin published, in 1901 (Archives de 
Parasitologie), a biographical sketch of Dujardin, with sev- 
eral illustrations, including this portrait and another one 
which is very interesting, showing him in academic costume. 
Thanks to the spread of information of the kind contained 
in that article, Dujardin is coming into wider recognition, 
and will occupy the historical position to which his researches 
entitle him, 
It was while studying the protozoa that he began to take 
particular notice of the substance of which their bodies are 
composed; and in 1835 he described it as a living jelly 
endowed with all the qualities of life. He had seen the same 
jelly-like substance exuding from the injured parts of worms, 
and recognized it as the same material that makes the body 
of protozoa. He observed it very carefully in the ciliated 
infusoria—in Paramcecium, in Vorticella, and other forms, 
but he was not satisfied with mere microscopic observation 
of its structure. He tested its solubility, he subjected it to 
the action of alcohol, nitric acid, potash, and other chemical 
substances, and thereby distinguished it from albumen, 
mucus, gelatin, etc. 
Inasmuch as this substance manifestly was soft, Dujardin 
proposed for it the name of sarcode, from the Greck, meaning 
sojt. Thus we see that the substance protoplasm was for 
the first time brought very definitely to the attention of nat- 
uralists through the study of animal forms. For some time it 
occupied a position of isolation, but ultimately became recog- 
nized as being identical with a similar suhstance that occurs 
in plants. At the time of Dujardin’s discovery, sarcode was 
supposed to be peculiar to lower animals; it was not known 
that the same substance made the living part of all animals, 
and it was owing mainly to this circumstance that the full 
recognition of its importance in nature was delayed. 
The fact remains that the first careful studies upon sarcode 
