THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL. 



Vol. X. JANUARY, 1889. No. 1. 



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 can Mofithly Aficroscopical Journal, Box 6jo, Washitigton, D. C. 



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Examination of Mould, (Pencilliuni glaucwm.) 



By Prof. II. L. OSBORN. 



»AML1NE, MINN. 



Every one is familiar with mould, such as accumulates on bread, jellv 

 or old boots after they have been left in damp places. Not everv one, 

 however, knows that mould is a vegetable and few understand its real 

 nature. With a microscope of good power (350 dia.) one can see 

 most of what is herein described ; with 350 diameters everything will 

 be made clear to the careful observer. 



There are many kinds of mould. Some are not Pencilliitm at all ; 

 others are quite like it. varying only in minute particulars. That is, 

 not all mould is Pcnc/ll/uj}i and not all Penciilium is P. gla7(C7im. 

 But this description will nearly fit any Penciilium and aid the student 

 in examining whatever species he happens to find. To be sure of get- 

 ting a specimen of Pe7icininm. put a moist cracker in a damp place 

 for 48 hours and then examine it for a sage-green spot which will prob- 

 ably appear. PeitciUiion is recognized with the naked eye bv its 

 color, by the low film it forms where it is attached, and by the fine dust 

 which can be blown from its surface. Other moulds common to such 

 places are either of a different color or they form a fuzzv, thicker 

 growth, reaching from ^ to | inch over the *'■ moulding" surface. 



I. Gross Anatomy. — Observe with naked eve the velvetv appear- 

 ance of the surface of Penciilium. Let fall a drop of water upon it 

 from a dropping tube, and notice ( i ) the powderv dust which the drop 

 has disturbed and which forms a fine cloud, soon dissipated, and (2) 

 that the water does not spread and moisten the surfice of the film, but 

 remains in droplets which can be shaken of!" the film. But alcohol and 

 some other fluids so dropped upon it spread and moisten it. 



A few instructive experiments may be named : — First, arrange six 

 vessels (tumblers are good) in pairs— two of distilled water, two of 

 distilled and sweetened water (using sugar enough to make a weak 

 syrup), and two containing moistened cracker or cake. Holding over 

 each vessel a piece of mould, shake ofl' upon the water and moist 



Copyright, 1889, by C. W. Smiley. 



