58 MEDICAL MYCOLOGY 



or, if they do not fall away readily, they are scraped off the blade into the 

 Petri dish by another blade. On reaching the laboratory, a few scales are 

 removed for microscopic examination after maceration in 40% KOH or some 

 other similar treatment. Then a very thin film of Sabouraud maltose or glu- 

 cose agar is poured into the plate containing the scales and detritus. Thus, 

 the latter are caught by the nutrient medium and held. To reduce chances of 

 bacterial contamination the scales may be moistened with alcohol for a short 

 time, but this does not prevent the growth of some of the hardy saprophytes 

 and may inhibit the growth of the more delicate pathogen. 



As soon as the colonies are visible to the naked eye, the suspicious ones 

 are marked with a glass-writing pencil, each being given a serial number. 

 The marked colonies are then transferred to Sabouraud 's sugar medium on 

 slants and to the conservation medium (without sugar). This transfer is 

 made early to prevent overrunning by the rapidly growing contaminants, such 

 as Aspergillus and Penicillium, which may be present. 



Isolations From Feces, Tongue Scrapings, etc, — Poured plates are allowed 

 to harden and then 25 points of contact are made in each with a platinum loop 

 repeatedly soiled with the infective material. After about four days, when the 

 colonies have developed, these are fished. In this way the percentage of 

 points of contact of material with the medium which contains similar colonies 

 gives a rough idea of the abundance of colonization in the material. (Dalmau 

 1930.) 



In connection with their studies with sprue, Weiss & Landron (1928) sug- 

 gest as follows: Emulsify a small quantity of feces in a test tube of sterile 

 distilled water and also in another tube containing whole ox bile in which has 

 been incorporated 20% concentration of glycerol. By means of a glass rod 

 bent at an angle of 30° a drop of each fecal suspension is spread over the 

 surfaces of the plates of Sabouraud agar (pH 6.3) containing 4% glucose and 

 20% glycerol ; incubate at 35° C. 



Dilution. — About three tubes of agar (or other liquefiable medium) are 

 heated gently on a water-bath (porcelain or glass beaker) until the agar melts. 

 It is then allowed to cool until the end of the tube containing the agar can 

 be held against the back of the hand without causing pain, i.e., until the 

 solidifying point is almost reached. The tube is inoculated by the method 

 suggested in simple transfer. After laying down the needle, the tube is rapidly 

 rolled between the palms, while it is in a vertical position, to mix the contents 

 thoroughly and scatter the inoculum. The loop is used to transfer a tiny drop 

 of the molten medium to the second tube two or three times. This in turn is 

 rotated, etc. The contents of the three tubes are then poured successively 

 into three Petri dishes lying on a level surface. If the agar fails to wet the 

 surface of the dish completely, the dish is tipped slightly to allow the agar 

 to flow over the whole surface of the bottom. It is then allowed to solidify 

 and is incubated bottom side up until growth is evident. Then individual 

 colonies are transferred to slants. Sometimes it is necessary to repeat this 

 process. In the above-mentioned processes it is desirable to work gently in 



