THE FLOWERLESS PLANTS. 



43 



one celled plant, multiplying by cell division. Study and 

 draw the little groups of cells that, for a time, cling 

 together. (See Fig. 19.) 

 The coherence between 

 the different plants of 

 these groups is very 

 slight, so that the groups 

 never become very large. 

 2. Put some of the 

 bark, bearing Protococ- 

 cus growth, in a glass of 

 water and set in a warm, 

 sunny place. Examine 

 drops of water, obtained 

 with the help of a cam- FlG . 19 ._p rotococcus , showingt hemulti- 



plication of the plant by cell division. 

 a, single plant ; 6, plant dividing into 

 two ; c, group of plants that have re- 

 sulted from repeated divisions of a 

 single cell. (X480.) 



el's hair brush from the 

 surface of the bark, daily, 

 for minute colorless oval 

 organisms like Fig. 20, 6, 

 which dart about rapidly. 



They are zoo spores, i.e., ani- 

 / mal-like spores. At first 

 glance one would not 

 suppose there was any 

 connection between the 

 moving animal-like or- 

 ganisms and the cells of 

 Protococcus. Neverthe- 

 less these moving organ- 

 isms are not animals, 

 but are one stage in 



a, plant preparing the development of the 



plant. They have re- 

 sulted from the division 

 of the cell contents into a number of parts. Their motion, 

 which will be studied later, is produced by alternate con- 





FIG. 20. Protococcus. 



for division into four large motile cells ; 

 6, one of the large motile cells, showing 

 the cilia. 



