THE BLASTOMYCETES 631 



Most forms disappear before the human host has reached twenty 

 years of age. 



(i) Microsporon andouini. 



Met \\\t\] in cliildren. Xever attacks the scalp of aduUs. Never 

 affects the beard and nails. Very intractable. It occurs as 

 a whitish sheath around the stumps of broken hairs. They 

 are round or oyoid spores, 3 to 4 /Lt. 

 (2) Trichophyton megalosporon. 



The endothrix variety is exclusively of human origin : the 



spores are seen in the interior of the affected hairs. 

 The ectothrix variety which affects the beard and nails is derived 

 from animals, the spores lying on the exterior of the hair. 

 The spores are large, 4 to 12 m. To facilitate examination 

 soak the hair in 10 per cent, caustic potash and then alcohol 

 and ether as for moulds. 



THE BLASTOMYCETES. 



These yeasts are round or oval unicellular organisms having hyaline 

 protoplasm in healthy, and granular protoplasm in old cells, surrounded 

 by a wall of cellulose. 



The torulas multiply by budding. 



The saccharomycetes by budding and spore formation. 



Spores are formed when the food materials are exhausted. 



They must have moisture and plenty of fresh air, temperature above 

 25° C. is best while fermenting nutrient liquids facilitate the formation 

 of spores. 



S. cerevisias. 



There are two typical brewery yeasts, the typical English, a " top " 

 fermentation variety, and the yeast of the Continental lager beer, a 

 " bottom " fermentation. The " top " and " bottom " are also known 

 as the " high " and " low " as they develop in high and low tempera- 

 tures respectively. They are 8 to 9 /a in diameter. Three to four 

 spores form in one mother cell. 

 There are " wild yeasts " as : — 



5. pastorianiis. There are three varieties with peculiarly shaped 



cells and having two to four spores in each 

 mother cell 

 ,, No. I is a bottom form and causes a disagreeable 



smell and a strong bitter taste in beer. 

 ,, No. 2 is a feeble top form of little importance. 



,, No. 3 is a dangerous " top " form causing tur- 



bidity and disease. 

 Bulgarian sour uiilk is used for therapeutic purposes. 



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