186 MICROSCOPIC FUNGI. 



of water on a glass slide. A thin glass cover is 

 placed over the drop of water, and the slide is 

 submitted to examination. For further satisfaction 

 it will often be found necessary to make carefully 

 a thin section of a pustule, and place this under the 

 microscope, a more troublesome but also much 

 more satisfactory method. Reference to the Ap- 

 pendix will soon determine the name and position 

 of the fungus, provided it belongs to the section to 

 which this volume is devoted. 



If it is thought desirable to mount the spores as 

 permanent objects, there is no obstacle to such a 

 proceeding. The spores of the different species of 

 Aregma, of Trijjhragjnium, and many of the Puc- 

 dnicp.j will be worth the trouble. We have tried 

 several media, and only adopted Glycerine or 

 Balsam ; either of these, especially the former, if 

 the greater difficulty of securely closing can be 

 overcome, will answer the purpose. 



It should be remarked that in the examination 

 of moulds, such as those of the genus Peronospora, 

 included in this work, if any fluid be added, the 

 acrospores are immediately disconnected from the 

 threads, and float in the medium ; so that if their 

 mode of attachment or arrangement would be 

 studied, that must be achieved without the addition 

 of any fluid whatever. 



The best methods of observing germination, the 

 production of zoospores, &c, have been detailed 

 already. 



