306 MEDICAL MYCOLOGY 



rarely more, fills about half the cell, and highly refractile corpuscles or motes 

 (probably metachromatic granules) showing Brownian movement are seen in 

 the vacuole. After these appear in culture, growth slows down, and reserves 

 of fat and glycogen are stored in preparation for formation of ascospores or 

 of resistant cells. 



The adult or durable cell (Fig. 40, 4 and 5) often persists unchanged in cul- 

 tures for months. This cell is larger with a vacuole, empty or containing a 

 single oil globule, occupying three-quarters of the volume. Fat is usually 

 stored in a large polar globule, occasionally as small globules around the 

 vacuole. The globules consist of an outer layer of albuminous substance en- 

 closing a semifluid emulsion of fatty substances. Shadow or senescent cells 

 are empty cell walls from which the contents have disappeared by rupture 

 or otherwise (Fig. 40, 6-9). 



The permanent cell is often still larger with a dark-colored wall thinner 

 than that of the normal cell. Vacuoles are usually absent, though occasionally 

 present, dark granules are present and, usually, fat globules also. 



Sometimes there results a pseudomycelium (Fig. 40, 10) composed of 

 adolescent cells, nonvacuolated cells with fat globules, and cells having finely 

 granular cytoplasm — the latter cells never seen save in pseudomycelium. Oc- 

 casional bizarre forms occur whose shapes are usually the result of multiple 

 abnormal budding. 



In the rare red yeasts even conidia are produced, especially in the genus 

 Sporoholomyces, whose method of conidial discharge sometimes causes it to 

 be placed in the Basidiomycetes, a very distantly related group of fungi. 



Physiologic characteristics should be noted, such as temperature limits 

 of sprouting, optimum temperature for growth as determined by colony size, 

 the temperature limits of formation of pellicles, etc. Sporulation should be 

 induced if possible. The media most commonly in use are gypsum blocks and 

 Gorodkova's agar. The yeast is cultivated for 24 hours on malt extract agar; 

 the growth is then scraped off and placed on a short cylinder of plaster of 

 Paris by means of a platinum spatula. The cylinder is placed in a sterile 

 Petri dish, filled to about half the height of the cylinder with sterile water. 

 Spores often appear in 1-8 days. 



Gorodkova's* agar may also be used. It consists of: distilled water 

 1,000 c.c, agar 10 gm., peptone 10 gm., beef extract 10 gm., sodium chloride 

 5 gm., glucose 2.5 gm. 



This enables the yeast to start growth, but the nutrients are quickly ex- 

 hausted and sporulation often results in 1-8 days. Some species which do not 

 form spores on either of these media will produce them on carrot in very old 

 cultures. Maneval (1924) reports spore formation in cultures kept in the 

 ice box. 



Once the asci have been obtained, their form, method of formation, and 

 the shape and size of their spores should be observed. It is often very difficult 



•Maneval (1924) omits the peptone and reduces the Liebig meat extract to 3 gm. in this 

 formula. He also recommends 15-20 gm. of agar. 



