110 STXTDY OF COMMON PLANTS. 



3. As the mould becomes still more abundant and 



extends beyond the bread on to the plate and 



sides of the bell-jar, notice under a lens its mode 



of growth. 



a. The production of horizontal hyphae that take 



root at intervals. 

 h. The sporangiophores rising into the air from the 

 place where the rhizoids are formed. 



IV. Examine the plant microscopically, taking first 

 some of the younger specimens, and proceeding from these 

 to the older ones. A drop of alcohol on the preparation, 

 followed by water, expels air and makes the examination 

 easier. The same end may be attained by mounting the 

 specimens in freshly boiled water. Observe 



1. The rooting hyphse, their structure and mode of 



branching. 



2. The structure of the sporangiophore, a long tube-like 



growth bearing the sporangium at its apex. 



3. Development of the sporangium. Study the latter 



carefully at different stages, beginning with speci- 

 mens that are white or but slightly colored, and 

 proceeding to older ones. Compare many speci- 

 mens, and when you are satisfied as to the develop- 

 mental history of the sporangium, make a series of 

 sketches illustrating it. 



Note. — Students rarely work this out independently, although 

 it involves but few difEculties, and these are easily overcome 

 by one who has a fair degree of patience and skill. The book 

 pictures are many of them incorrect, hence the necessity of 

 close attention to details of structure. 



4. Under the highest power available, study the form 



and structure of the spores. Make drawings illus- 

 trating the different forms. 



