COLONIAL PROTOZOA 69 



colony composed? How do they differ in size, position, 

 and shape? 



2. Structure. Note the size, shape, and large number of 

 cells which make up the body of the organism. How are 

 the cells connected with each other? Under high power 

 make out the flagella of the cells. How many has each cell? 

 With what part of the cell are they connected? 



Make a careful drawing of a group of cells, their structure, 

 and connection to other cells. 



n. Physiology. 



1. Reproduction. (a) Asexual. Certain cells, partheno- 

 gonidia, migrate from the outer wall into the interior of the 

 sphere and there, without fertilization, give rise to small 

 colonies by repeated divisions. 



(6) Sexual. Other cells which move into the interior of 

 the sphere are specialized reproductive cells. The egg 

 (macrogamete) is large, the spermatozoids (microgametes) 

 are small. These two kinds of cells fuse or conjugate and 

 the fertilized egg develops into a new colony. 



Make drawings of different stages of reproduction, both 

 sexual and asexual. 



Would you regard Volvox as a unicellular colony or as a 

 very simple multicellular organism? Give reasons for your 

 conclusion. 



