THE LARGE GROUP OF THE SMALLEST OlUiVMsMs |r,.-. 



conditions are favorable for germination. When the zyjrotr .l,„..s 

 germinate, two new individuals come direetly from it. 



Many other forms of algae may be found in fresh and .s.h w.-.i.t. 

 Some, like Scenedcsmus, occur in colonies, their end cells being ..ftcn 

 provided with characteristic spines. Another colony of gr,.,.,, cells 

 Pediastrium, made up of a flat plate of sixteen cells, is also frecpiently 

 seen. These are only a few of the many forms of green algae that 

 may be found in a drop of water debris tak(Mi from a (iniet poml 

 bottom. 



Bacteria 



Various kinds of bacteria are common in a drop of i)ond water or 

 hay infusion. They are sometimes seen moving through the water, 

 but more often are massed together in a scum covering the surface 



""a^o?. O^tfJ /f#^^' 



cocci 



op oo oo 



«■& S? 



QO QO ^ 



ig^Hfl GO .. ao 



rmcrococcA diplococci staphylococci streptococci 

 Forms of l);icleria. 



of the water. Three large groups of bacteria ha\-e been established 

 according to their shape, coccus, baccillus, and spirillum. The coccus 

 or spherical-shaped bacteria may live singly, as micrococci. Anotlier 

 form, the diplococci, divides and remains attaclied s(j as to form 

 pairs ; a third, streptococci, reproduces to form chains ; while a fourth. 

 staphylococci, forms irregular groups of eight cells or more, resem- 

 bling a bunch of grapes; Sarcina divides in three directions to pro- 

 duce cubical packets. The rod-shaped bacteria, or bacilli, \i\ry a 

 good deal in size and shape, as well as in tiieir ability to form spores, 

 some being very short, others many times longer than wide. The 

 third type, comprising the spirilla, are cur\e(l or twisted in shape, 

 and move through the water rapidly by spiral movement. This 

 form can often be seen hi a droj) of pond water or hay infusion. 

 BacilH and spirilla move by means o( Jlagdla, protoplasmic threads 



