2258 



Journal of Applied Microscopy 



Carter (Jour. App. Mic, April, 18!»8) and subsequently recommended by 

 Dawson (Jour. App. Mic, Oct., 1899) most satisfactory. The surprise is that 

 it is not generally recommended in text-books. It is certainly admirably adapted, 



especially to class work. One point about 

 getting perfectly white serum. The usual re- 

 commendation of using the serum after it has 

 stood for 24 to 48 hours does not give satis- 

 factory results, as the serum will always be 

 somewhat colored. A better practice is to put 

 the serum drawn off at the end of 48 hours 

 into a well-stoppered bottle, add a little chloro- 

 form and let it stand for weeks and even 

 months. In time, the blood corpuscles sub- 

 side, leaving a perfectly clear serum. This, 

 when coagulated, is as white as the white of 

 ^SS- The chloroform is removed by heating 

 the serum to be used at a 56°C. for 30 min- 

 utes. For the isolation of diphtheria bacilli 

 the following method will prove fairly satis- 

 factory. Round flat flasks, containing Loefifler's 

 blood serum mixture, are placed in the coagu- 

 lator or sterilizer on a perfectly horizontal 

 plane, and the serum coagulated. It then pre- 

 sents a perfectly white smooth surface. The 

 swab is run lightly over this surface, and the 

 flasks inoculated, bottom side up, for 18 to 24 hours. At the end of that time 

 any colonies which have appeared on the surface are removed by means of a 

 platinum needle with the point bent at a right angle and examined. The minute 

 colonies which appear at this time of incubation are, as a rule, either micrococci 

 or diphtheria bacilli. By examining several colonies the right colony may be 

 finally discovered. The reason for using flasks instead of plates, although the 

 latter are more convenient, is that the flasks can be hermetically sealed by means 

 of the paraffin stoppers and kept ready for use. (See Fig. 2.) 



III. 



A Ready Method for Manipulating and Fastening Paraffin Sections. — The follow- 

 ing method will be appreciated by those who exhaust their patience on trying to 

 handle and fasten to the slide paraffin sections : The paraffin sections are 

 floated in warm water. The center of the slide is painted with a saturated solu- 

 tion of celloidin in oil of cloves. With the corner of a piece of filter paper one 

 or more of the sections are lifted out by placing the paper underneath the sec- 

 tions. The latter adhere by capillary attraction to the filter paper. The paper 

 holding the sections is then inverted over the celloidin-oil and gently pressed. 

 The sections adhere firmly to the slide, and the paper can be readily removed 

 without carrying the sections along. The subsequent treatment is the one 

 usually recommended. By making a rather thick film of celloidin-oil and then 



Fig. 2. — Flask, plugged and stop- 

 pered, containing coagulated blood- 

 serum and showing colonies of 

 diphtheria bacilli. 



