The Substance Which Is Alive in Plants 141 



jelly; that is what protoplasm looks like, and that is precisely 

 what it is.* 



While protoplasm for the most part can be observed in plants 

 only by aid of the microscope, there are cases in which it occurs 

 in masses sufficiently large to be studied by the unaided eye, and 

 to be taken in the hand. Everybody has seen those soft, whitish, 

 slimy masses which are flattened against decaying wood in damp 

 dark places, such as the rotten underpinning of old buildings, 

 in cellars and dark greenhouses, or on old shaded tan-bark, 

 whence they are known as " Flowers of Tan." These are called, 

 scientifically, Slime-molds, and they are practically pure naked 

 protoplasm, the accessibility of which has made these low plants 

 very favorite objects for protoplasmic studies. 



Such is the appearance of living plant protoplasm as seen 

 by the eye or through an ordinary microscope; and try as one 

 will, he can see little more. The supreme importance of proto- 

 plasm among earthly substances has of course acted as a stimulus 

 to the most thorough researches into its structure; and all the 

 highest powers of the microscope, and all the most refined de- 

 vices and methods known to microscopical science, have been 

 brought to bear upon it. Yet these efforts have yielded little 

 additional knowledge, and even that little has been left involved 

 in uncertainty and controversy. We do not even know what tex- 

 ture the protoplasmic substance possesses. Some investigators 

 have concluded that such protoplasm as the reader has seen 

 streaming in plant-hairs is a loose network of fine elastic fibers, 



* The streaming of Protoplasm is thus vividly visualized, though with some ex- 

 aggeration natural at that time, by Huxley, "Currents similar to those of the hairs 

 of the nettle have been observed in a great multitude of very different plants, and 

 weighty authorities have suggested that they probably occur, in more or less per- 

 fection, in all young vegetable cells. If such be the case, the wonderful noonday 

 silence of a tropical forest is, after all, due only to the dulness of our hearing; and 

 could our ears catch the murmur of these tiny Maelstroms, as they whirl in the in- 

 numerable myriads of living cells which constitute each tree, we should be stunned, 

 as with the roar of a great city." The Physical Basis of Life in his Collected Essays, 

 New York, I, 136. 



