182 



PRACTICAL BOTANY 



166. Gloeocapsa: reproduction. After a Grloeocapsa plant has 

 been growing for a time it may divide into two new plants. 

 The wall divides, completing the separation of the protoplasm 



into two cells and thus two new 

 plants are formed (Fig. 152). 

 The separation of the protoplasm 

 really begins before the walls 

 push mward, but this protoplas- 

 mic division cannot readily be 

 observed. The new 

 plants, before they 

 become free from the 

 mass of jelly inclosing 

 them, may again re- 

 produce themselves, 

 so that four, eight, or 

 even a much larger 

 number may be united 

 in one colony. In such 

 cases the plants are 

 held together so very 

 closely that they of- 

 ten do not assume the 

 spherical form. 



Each new Glceocapsa 

 plant is essentially the 

 kind that its parent 

 ■was before the divi- 

 sion occurred. In fact 

 the parent plant by 

 division becomes di- 

 rectly two new indi- 

 viduals. This method of reproduction l)y division or fission 

 •(splitting) is the simplest known in the plant kingdom, and 

 is characteristic of the simplest animals as well as of the sim- 

 plest plants. 



Fig. 153. Nostoc 



At the left (^) are several of the Nostoc halls, which 

 appear as glistening, rounded masses (natural size). 

 At the right (B), inclosed in gelatinous material, 

 are a few chains of Nostoc plants which have been 

 taken from one of the balls and greatly magnified. 

 In the chains several of the enlarged heterocysts 

 may be seen 



