FUNGI 



261 



about 28° C. After 4 or 5 days, begin to examine. A 40 per cent solu- 

 tion of cane-sugar in the juice of prunes is also a good nutrient solution. 

 If you find the perithecial stage, keep the culture going in a test-tube; 

 and it would be wise to pickle a lot, lest something might happen to the 

 culture and you might not find the rare stage again. 



For class use or for permanent preparations it is best to select 

 rather young material which shows various stages in development, 

 from the swollen end of the hypha to the ripe spore (Fig. 68). Per- 

 manent preparations of the conidial stage, as shown in Figure 68, and 

 also of the coiled twisted filaments which initiate the ascosporic stage, 

 should be made by the Venetian turpentine method or by the glycerin 

 method. 



A B 



Fig. 68. — Asp'r'jillus: from material growing on a hectograph pad; fixed in chromo-acetic acid, 

 stained in eosin, and mounted in glycerin; A-£, successive stages in development. X375. All such 

 material is more satisfactory when mounted in Venetian turpentine. 



Fix in 1 per cent chromo-acetic acid (1 g. chromic acid, 1 c.c. acetic 

 acid, and 100 c.c. water) for 24 hours; wash in water 24 hours, stain 

 sharply in eosin, transfer to 10 per cent glycerin, and follow the Vene- 

 tian turpentine method. 



Material may be fixed in corrosive sublimate-acetic acid (corrosive 

 sublimate 2 g., glacial acetic acid 2 c.c, and water 100 c.c). Use it hot 

 (85° C). One minute is long enough. Wash in water and add, a few 

 drops at a time, the iodine solution used in testing for starch. At first, 

 the brownish color caused by the iodine will disappear, but after a cer- 

 tain amount has been added the brownish color will remain. Stain in 

 eosin or iron-haematoxylin and follow the Venetian turpentine meth- 

 od. 



A very rapid method for this and for similar small filamentous forms 

 may be added. Forms as large as Thamnidium elegans can be mounted 

 successfully by the following method. 



