THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL. 



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



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 matters, and all books, pamphlets, exchanges, etc., should be addressed to Ameri- 

 can Monthly Microscopical Journal, Box 6jo, Washington, D. C. 



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 Trubner c5n> Co., 37 Ludgate Hill, London, accompanied by the yearly price of 

 five shillings. 



Examination of Mould. (Pencillium glaucum.) 



By Prof. H. L. OSBORN. 



HAMLINE, MINN. 



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

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

 however, knows thai; mould is, h vegetable and few understand its real 

 nature. With a microscGr^Qf^p^ijnojYaejfc^/sfiQi-dia.) one can see 

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

 be made clear to the BdadW©l^tyeMe mage 



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

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

 not all mould is Pencillium and not all Pencilliui?i is P. glaticum. 

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

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

 ting a specimen of Pencillium , put a moist cracker in a damp place 

 for 4S hours and then examine it for a sage-green spot wdiich will prob- 

 ably appear. Pencilliu?n is recognized with the naked eye by 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 fuzzy, thicker 

 growth, reaching from \ to | inch over the " moulding" surface. 



1. Gross Anatomy. — Observe with naked eye the velvety appear- 

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

 from a dropping tube, and notice (1) the powdery 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 surface of the film, but 

 remains in droplets which can be shaken off 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 off upon the water and moist 



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