BIOLOGY FOR YOUNG BEGINNERS. 



345 



boats often have a tiny red window, or port-hole, called the " eye- 

 spot." If you watch long and carefully, you can see the little boat- 

 man pull in his oars (Fig. 12), as if to rest. But, if you shake the 

 water, and then put it in the sun, out go the oars again, rowing faster 

 than ever. The little pear-shaped cells do not have a tough, cellular 

 sac ; these independent little sailors seem to jump out of the boats 



Fig. 11. Protococcus Boats. 



Fig. 12. Protococcus, or Berrt- 

 Boat, with Oars pulled in. 



entirely and swim about quite naked (Fig. 13). After they have 

 bathed to their hearts' content, they seem to retire quietly to the 

 sands and dress themselves again ; that is, each one builds around 

 himself a new wall, or boat, in which he rests till he needs another 

 dip. The larger kind try to be more respectable ; they stay in their 

 boats in a dignified and proper manner. Iodine kills them, and then 

 you can see where the little oars are pushed through the row-locks in 

 the sides of the boat. These oars are called cilia a word which 



Fig. 13. Pear-shaped Cell without a Sac, or the Boatman without a Boat. 



means eyelashes. When the little sailors are getting tired, and just 

 before they die, you can see these eyelash oars quite plainly, they 

 move so slowly ; but, when they are vigorous and the day is sunny, the 

 oars move so fast you cannot see them. No Columbia or Cambridge 

 crew can begin to pull with these protococcus boatmen. Besides being 

 good oarsmen, they are also good builders. You may often see them 

 breaking up the old boats by cleavage and fission, just as the carpen- 

 ters break up the old houses. 1 



And so we have followed our quaint little friend, the protococcus, 

 through all his occupations chemist, carpenter, boatman, and ship- 

 builder. Now, I am sure you will never again pass by an old fence, 

 or a pool of green water, without thinking of the wonderful little arti- 



1 The kind of berry-moulds that grow on old wood and stones, and in the snow, is 

 called still protococcus ; that which grows in old water, and moves about by oars, is 

 called moving protococcus. 



