262 BIOLOGY AND ITS MAKERS 



(with slight verbal alterations) says : "The spectacle afforded 

 by the wonderful energies imprisoned within the compass of 

 the microscopic cell of a plant, which we commonly regard 

 as a merely passive organism, is not easily forgotten by one 

 who has watched its movement hour by hour without pause 

 or sign of weakening. The possible complexity of many 

 other organisms seemingly as simple as the protoplasm of 

 the plant just mentioned dawns upon one, and the compari- 

 son of such activity to that of higher animals loses much 

 of its startling character. Currents similar to these have 

 been observed in a great multitude of very different plants, 

 and it is quite uniformly believed that they occur in more 

 or less perfection in all young vegetable cells. If such be 

 the case, the wonderful noonday silence of a tropical forest 

 is due, after all, only to the dullness of our hearing, and could 

 our ears catch the murmur of these tiny maelstroms as they 

 whirl in the innumerable myriads of living cells that con- 

 stitute each tree, we should be stunned as with the roar of a 

 great city." 



THE ESSENTIAL STEPS IN RECOGNIZING THE LIKENESS OF 

 PROTOPLASM IN PLANTS AND ANIMALS 



Dujardin. This substance, of so much interest and im- 

 portance to biologists, was first clearly described and dis- 

 tinguished from other viscid substance, as albumen, by Felix 

 Dujardin in 1835. Both the substance and the movements 

 therein had been seen and recorded by others: by Rosel 

 von Rosenhof in 1755 in the proteus animalcule; again in 

 1772 by Corti in chara; by Mayen in 1827 in Vallisnieria ; 

 and in 1831 by Robert Brown in Tradescantia. One of these 

 records was for the animal kingdom, and three were for 

 plants. The observations of Dujardin, however, were on a 

 different plane from those of the earlier naturalists, and he 



