THE CELL 103 



thirty, forty bodos throw themselves upon him, eviscerate 

 and devour him completely (Stein)." 



Here is what Mr. Haeckel has .to say about the parasitic 

 habits of some cells. 



"By parasites in the narrower sense, we understand in 

 modern biology only those organisms which live on others 

 and derive their nourishment from them. They are numer- 

 ous in all the chief divisions of the plant and animal king- 

 doms and their modifications are of great interest in con- 

 nection with evolution. No other circumstance has so 

 profound an influence on the organisms as adaptation to 

 a parasitic existence. 



"I have already spoken of the many peculiarities of me- 

 tabolism in the ubiquitous bacteria ; while many of them 

 cause putrefaction, they at the same time feed on the 

 parts of other organisms which have died. The fungi feed 

 for the most part on the .decayed remains of plants and 

 the product of putrefaction which accumulates on the 

 ground. In this character of scavengers they play the 

 same important part on land as the sponges do at the bot- 

 tom of the sea." 



I must here tell the reader something about the cell 

 colony called the volvox : 



These cells bunch themselves into colonies of about 

 twelve thousand individuals. Some are male and female 

 and some only workers or neutrals. The common labor- 

 ers or neutral cells are all provided with hands which 

 they use to push and propel themselves through the water 

 backwards or forwards like a raft or submarine. Five 

 thousand like the galley slaves of old paddle the water 

 with their arms at the same time and in that way trans- 

 port the other seven thousand males and females to such 

 places as they may choose to go. Just consider this, for a 

 minute : a boat or raft pushed through the water by five 



