TYPES OF CRYPTOGAMS; THAiLOPHYTES 257 



305. Classification of Types studied. 



DiATOMACEiE. Yellowish. 



Diatoms. 



Ctanophyce^. Blue-green or some similar color. 



Oscillatoria. 



Chloeophyce^. Green. 



Pleurococcus, Spirogyra, 



Vaucheria, Nitella. 

 PhjEOphycEjE. Olive. 



Fucus. 

 Flobide^. Ked. 



Nemalion. 



Polysiphonia. 



THE STUDY OF BLACK MOULD (RHIZOPUS NIGRICANS) 



306. Occurrence. — This mould may be found in abundance on 

 decaying fruits, such, as tomatoes, apples, peaches, grapes, and cher- 

 ries, or on decaying sweet potatoes or squashes. For class study it 

 may most conveniently be obtained by putting pieces of wet bread 

 on plates for a few days under bell-jars and leaving in a warm place 

 until patches of the mould begin to appear. 



307. Examination with the Magnifying Glass. — Study some of 

 the larger and more mature patches" and some of the smaller ones. 

 Note: 



(a) The slender, thread-like network with which the surface of 

 the bread is covered. The threads are known as hyphce, the entire 

 network is called the mycelium. 



(6) The delicate threads which rise at intervals from the myce- 

 lium and are terminated by small globular objects. These little 

 spheres are spore-cases. Compare some of the spore-cases with 

 each other and notice what change of color marks their coming to 

 maturity. 



308. Examination with the Microscope. — Sketch a portion of the 

 untouched surface of the mould as seen (opaque) with a two-inch 

 objective, then compare with Fig. 189. 



