and Laboratory Methods. 1565 



blackens the myelin sheath of the nerve-fibre. When the degree of blackening 

 desired has been obtained, wash the nerve thoroughly with distilled water. 



A piece of the nerve may now be transferred to a drop of glycerine on a slide, 

 teased apart, and used at once for a demonstration. Other pieces should be 

 imbedded in paraffin for sectioning. It is convenient to arrange the pieces so 

 that, in the same block, some will be cut lengthwise and others transversely. 

 The sections should be counter-stained with a saturated aqueous solution of 

 fuchsin-S for twenty-four hours. Gilbert L. Houser. 



Laboratory of Animal Morphology, The State University of Iowa. 



A Short Method for the Widal Test. 



One of the inconveniences of this test is the length of time required to get a 

 broth culture in which the typhoid bacilli are sufficiently numerous and active to 

 permit of use for the test. If the bacilli are too few in number the " clumps " 

 are not only small, but are also slow in forming; and if they are not active 

 agglutination does not take place readily. Eighteen hours is the time usually 

 specified as being necessary to get a broth culture in proper condition for use, 

 but this length of time makes it impossible to apply the test during the day on 

 which the culture was started, so the tube must be inoculated late in the after- 

 noon of the day before it is to be used in order that it may be ready for the test 

 at a seasonable hour the next morning. If the culture is not then used rather 

 promptly at the specified time, agglutination is likely to be found to have taken 

 place spontaneously in the tube. The culture is thus rendered useless and a 

 delay of eighteen hours more is required to get another one ready. The writer 

 has found that the time can easily be shortened to six or eight hours and that 

 cultures started in the morning can be used in the afternoon of the same day. 

 The essential point of the method is to start the culture in wann broth. The 

 details are so simple as scarcely to require explanation. By means of the 

 platinum loop a small mass of the growth is removed from the stock culture on 

 agar and is well mixed with eight or ten cubic centimeters of broth by rubbing 

 the mass against the inside of the tube below the surface of the liquid. The 

 tube is then gently tapped for a minute or so in order to insure the thorough 

 and even dissemination of the bacilli throughout the broth, and is heated until 

 it feels comfortably warm to the hand by holding well above the gas flame. A 

 tumbler is then heated still warmer by holding it inverted over the flame and the 

 culture placed in it resting on a wad of cotton and the whole put into the incu- 

 bator for six or more hours. It is sometimes well to remove the tube once from 

 the incubator and tap it gently for a few seconds in order to mix the denser 

 growth in the bottom with the upper portion of the broth. The opacity and 

 opalescence of the liquid will show when sufficient growth has taken place. On 

 several occasions cultures only six hours old have been used with perfect satis- 

 faction, but, of course, the bacilli are neither so active nor so numerous as in 

 cultures which have stood in the incubator for two or three hours longer. 

 University of Rochester. CharLE.S Wright Dodge. 



