2524 Journal of Applied Microscopy 



sterilization may be safely stopped. The sterilization of the glassware should 

 be done either before the preparation of the gelatine is begun or while it is being 

 made, so that the vessels will be ready to receive the gelatine as soon as it is 

 filtered. 



When the gelatine has been distributed into test-tubes or bottles it must be 

 given a final sterilization. This is done in the steam sterilizer and never in the 

 hot-air sterilizer, where it would only be evaporated and charred. The steam 

 sterilizer may be either an Arnold or the simpler form shown in Fig. 2. In such 

 a sterilizer the gelatine is placed and the water quickly brought to a boil ; the 

 material is allowed to stay in the steam for twenty minutes and then removed 

 and cooled. It is allowed to stay at the temperature of the room for twenty- 

 four hours, when it is again heated as in the first instance and again allowed to 

 stand, and heated for the last time on the third day. This method is known as 

 the discontinuous method of sterilization. The theory is that on the first day 

 all of the bacteria are killed which are not in a spore form. The spores it would 

 be impossible to kill with steam unless the exposure extended over several hours, 

 which would injure the gelatine. While in the media, the spores which were 

 not killed germinate and the next day the young forms are readily killed. If 

 any should not be destroyed they are killed the third day. The gelatine should 

 be kept in a cool, dark place until it is used. If a cloudiness or specks appear 

 it means that it is not sterile and must be discarded. W. D. Frost. 



University of Wisconsin. E. G. HASTINGS. 



According to Brinckerhoff and Tyzzer and Professor G. Sims Woodhead, the 

 following wet method for blood films gives excellent results : 



1. Hold the wet film, wet side down, in the mouth of a wide bottle, half filled 

 with ordinary 40 per cent, solution of formic aldehyde, for about five seconds. 



2. Drop, still wet, film side downwards, into absolute alcohol. Leave fifteen 

 minutes, or, if more convenient, as long as forty-eight hours. 



3. Blot off excess of alcohol, and move cover-glass to a dry part of the 

 blotting-paper. 



4. Immediately, before any drying occurs, drop on a few drops of eosin- 

 methylene blue stain (Jenner's stain) ; cover with a watch-glass ; stain for two 

 minutes, no longer. 



5. Allow excess of stain to run off the cover-glass, and rinse at once in a 

 bowl of distilled water. 



6. Blot off excess of water. 



7. Dehydrate very rapidly in absolute alcohol, merely dipping in and with- 

 drawing as quickly as possible. 



8. Wash off alcohol in first xylol rapidly ; wash in second xylol ; drop on 

 fresh xylol. 



9. Mount in xylol balsam. 



Scott insists upon the importance of using only pure distilled water to wash 

 off excess of stain and cover-slips which are quite free from acid. The blocd 

 film must not be allowed to dry at any stage. — Journal of State Medicme. 



