84 PRACTICAL BOTANY. 



Protococcus, and yet they are frequently found in gather- 

 ings from still water. 



References for Reading. Bennett and Murray's " Cryptogamic 

 Botany," pp. 296-298; Carpenter's "The Microscope," pp. 495-498; 

 Goebel's "Classification of Plants," pp. 39-41. 



PKOTOCOCCUS. PRACTICAL STUDIES. 



Protococcus viridis is abundant on the north side of 

 old unpainted buildings and fences and on trees, forming 

 a very noticeable green incrustation ; it is especially dis- 

 tinct in wet weather. It may be obtained for study at 

 any season of the year from these sources. It also fre- 

 quently occurs during hot 

 weather in abundance in 

 stagnant pools of water. 



1. Place a quantity of 

 Protococcus in alcohol for 

 |c several hours and observe 

 the yellowish-green color 

 \ imparted to the alcohol 

 |) by the chlorophyl. Mount 

 Sfy some of the cells so 

 r yj treated and observe that 

 the color has been en- 



FIG. 42. Protococcus in the vegetative tirely removed. 



condition, showing the mode of multi- 2. Mount a little fresh- 

 plication by cell division. 



ly gathered Protococcus 



in water. Notice that while many cells occur singly, others 

 occur in variously arranged groups. (See Fig. 42.) The 

 positions of the cells in groups show that the organism is 

 reproduced by cell division. Observe a reddish spot or 

 tint in many of the cells. Hsematococcus, a form of Pro- 

 tococcus found in stagnant rain water, receives its name 

 from the abundance of this red pigment. The chlorophyl 



