Journal of Applied Microscopy. 



593 



METHODS IN PLANT HISTOLOGY. 



Charles J. Chamberlain. 



IX. 



ASCOMYCETES. 



This group, popularly known as the " sac fungi," contains an immense 

 number of saprophytic and parasitic forms. Yeast, green mould on cheese and 

 leather, leaf curl of peach, black knot of cherry and plum, and the powdery 

 mildews are familiar to everyone. The few objects selected will enable the 

 student to experiment, but he must not be discouraged if success does not 

 crown the first attempt, for the group presents many difficulties. 



Saccharoniyces. — Until somewhat recently it was considered rather difficult to 

 demonstrate the nucleus of the yeast cell. With fresh growing yeast, the follow- 

 ing method by Wager should be successful. (See also the January, 1899, 

 Journal.) Fix in a saturated aqueous solution of corrosive sublimate for at 

 least twelve hours. Wash successively in water, thirty per cent, alcohol, seventy 

 per cent, alcohol, and methyl alcohol. Place a few drops of alcohol containing 

 the cells on a cover, and when nearly dry add a drop of water. After the yeast 

 cells settle, drain off the water and allow the cells to dry up completely. Place 

 the cover, or slide, with its layer of cells in water for a few seconds, and then 

 stain with a mixture of fuchsin and methyl-green, or fuchsin and methylen blue. 

 Mount in glycerine or in balsam. 



Em'otium. — For class use or for permanent preparations it is best to select 



JOUR upp mc 



Fig. 28. Eurotium. 



From material growing on a hectograph pad. Fixed in chromo-acetic acid, stained 



in eosin, and mounted in glycerine. A-E successive stages 



in development. X 375. 



rather young material which shows various stages in development, from the 

 swollen end of the hypha to the ripe spore. The nuclei are exceedingly small, 

 and can hardly be demonstrated with eosin. Iron alum hgematoxylin would be 

 better. A saturated solution of corrosive sublimate in fifty per cent, alcohol, 

 used hot, can also be recommended for fixing. Mount in glycerine. For 

 paraffin sections use the safranin-gentian violet-orange combination, and mount 

 in balsam. 



Other filamentous forms, like Penicillium, may be treated in the same way. 



