266 BIOLOGY AND ITS MAKERS 



evident. Professor Joubin published, in 1901 (Archives 

 Parasitologic), a biographical sketch of Dujardin, with sev- 

 eral illustrations, including this portrait and another on< 

 which is very interesting, showing him in academic costume. 

 Thanks to the spread of information of the kind contain< 

 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 Greek, meaning 

 sojL 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 substance 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 



