136 palmf:r : 



water ; only, in that case, he shall have this burden upon his 

 shoulders in the form of a substance twice the specific gravity 

 of water. Or, if it be suggested that the burden be too heavy 

 for the human frame, aud if we may be permitted to consider 

 weight and distance as convertible terms, he may drop all this 

 weight and transport himself and his bones 23.3 miles per 

 hour in any way that seems good to him — so always he does 

 it with his own native strength. 



We might rest here with the notion that we had arrived at 

 some adequate appreciation of the energy exhibited b}'^ the 

 protoplasm of the crawling diatom. But we should deceive 

 ourselves in this. For one of these diatoms will, without any 

 trouble to itself, carrj^ along with it, or push out of its way, 

 weights of other filamentous diatoms not in motion, that may 

 equal twent}^ times its own weight. These are frequent occur- 

 rences. We may safely say, therefore, that we have here the 

 equivalent of the man progressing at 23.3 miles per hour, and 

 dragging along with him a weight of 2520 pounds beside his 

 bones ; or else he may go unhampered 466 miles per hour. 



We ma}" now begin to see the little worth of the sa\nng : 

 " The mass of the diatom is small, its progress slow." If the 

 whole mass is small, the mass of the animating protoplasm is 

 yet smaller, and the work done by this minute portion of 

 living matter is not small relatively, but very large. Propor- 

 tionately to its volume, this protoplasm gives an enormous 

 output of energy, and applies it for the purpose of locomo- 

 tion in a way which, on the face of it, and so far as the 

 arrangement is understood, would seem poorly adapted for the 

 highest efficiency. 



It is going to be said that this argument proves too much. 

 It is going to be pointed out, with a certain show of glee, that 

 the miserable jelly lining the walls of the diatom frustrule 

 can by no possibility exhibit such capacity for wt^rk. I shall 

 be told that if these estimates be correct we must call u]ion 

 environmental forces to explain diatom motile activity. ,So 

 shall osmosis lift again its diminished head, and Jackson and 



