ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



103 



attached firmly at one end to a block of hard rubber (fig. 14), the other 

 end moving freely over a similar hard rubber block, to which is 

 fastened the screw closing the current ; the adjustment of the tempera- 

 ture is secured by movement of the screw. The low voltage current is 

 best obtained from a series of resistance units connected in a lighting 

 circuit (fig. 15) ; a 32 c.p. lamp A connected in series with a number of 

 coils of small iron wire, B B, answer the purpose. The circuit passes to 

 the regulator C, then to the magnet of the circuit breaker D, and back 

 to some point on the wire resistance, which is regulated by changing the 

 connection H until it gives a current just sufficient to operate ! the 

 magnet ; the regulator should be so arranged that the heating circuit is 

 closed when the magnet pulls the armature F up against the binding 

 post E. 



Linc no volts 



HO VOLT 

 LAMP 



o 



A a 



€b 



heating coil. 



Fig. 15. 



Observations on the Drigalski-Conradi Method of Diagnosing' 

 Typhoid Bacilli.* — Ed. Monti has shown that by means of the Drigalski- 

 Conradi medium, or other chosen media, or even the agglutination 

 reaction, a positive diagnosis of a typhoid-suspected colony cannot be 

 assured. For on this media there grow different colonies which 

 resemble typhoid bacilli and more or less agglutinate with typhoid 

 serum ; and, further, typhoid colonies can be found which agglutinate 

 less actively than other species (Lipschutz, Klinger, etc.). 



With our present knowledge of the biology of typhoid bacilli it is 

 useless to hope to make a certain diagnosis in 16-20 hours, or even to 

 separate and identify the specific organism from the fasces or urine. 

 To control the suspected colony thoroughly necessitates 2-3 days. 



Further, a negative result with the Drigalski media does not exclude 

 the presence of typhoid. 



The author could find the specific germ only in 5 out of 12 cases. 

 His repeated negative results agree with those of Lipschutz, Krause, 



* Arohiv Sci. Med., xxix. No. 4. See also Centralbl. Bakt., xxxvii. (1905) p. 267- 



