Pteridophytes Filicales 243 



The sperm, which in Marsilia has an unusually large number 

 of turns in the spiral, is easily mounted whole. When the sperms 

 have become numerous, put several megaspores upon a slide and 

 heat gently until dry. Then wet the preparation in any alcohol and 

 stain sharply in acid fuchsin. Dehydrate in absolute alcohol for 

 at least 10 minutes, clear in clove oil, and mount in balsam. Such a 

 preparation will often show a score of sperms in the gelatinous 

 funnel leading down to the neck of the archegonium. 



Azolla is not difficult to obtain, and it is easy to get a series of 

 stages in the development of the micro- and megasporangia ; but 

 it is not at all easy to find the gametophytes, since the spores ger- 

 minate only after they have been set free by the decay of the plant. 



