122 



TAXONOMY 



Some of the yeasts and molds possess the power of produc- 

 ing disease conditions in the human body. 



Relationship to Cyanophyceae. The bacteria taking 

 the whole group into consideration are without doubt 

 more closely related to the Cyanophyceae, or blue-green algae, 

 than to any other plants. The blue- 

 green algae are single- celled plants which 

 usually form themselves into threads or 

 filaments, and reproduce in the main by 

 fission, similar to bacteria (Fig. 37). 

 The filaments branch and there is a 

 specificity of function among the vari- 

 ous cells. They are very closely related 

 to the Chlamydobacteriaceae and the 

 Thiobacteria. Some forms also resemble 

 the lower bacteria in shape. They are, 



FIG. 37. Anabena , . , , 1 . 



rariabilis. Cyano- as before stated, filamentous, and many 

 phyte. After spe cies possess sheaths. The blue-green 



Schmidt and Weis. 



algae compose the remaining portion of 

 the connecting link between the bacteria and the chloro- 

 phyll-bearing plants. In addition to their similarity in 

 form they secrete a gelatinous substance from their cell 

 walls similar to some species of bacteria. Some forms 

 (Oscillariae) are motile. They differ from the bacteria 

 and show an advance over them in the possession of a 

 primitive nucleus and chlorophyll in the outer layers of 

 their protoplasm. The bluish green coloring matter is 



