3 82 



Pathology. The spleen is much enlarged and soft. 

 The liver shows necrotic foci due, according to 

 Levaditi, to an actual invasion of the tissue by spiro- 

 chaetes. Stain sections of liver by Levaditi's method. 



Mode of Transmission. This is effected by Argas 

 miniatus. This tick is a night feeder. A temperature 

 of about 35 G. is necessary for successful transmission. 

 The ticks remain infective for one month after feeding. 



To Stain Spirochaetes in Sections. Levaditi and 

 Manoulian* give the following as their latest formula. 



1. Fix small pieces of tissue, i millimetre thick, 

 in formalin. Harden in ninety-five per cent, alcohol 

 one hour. Then into distilled water until they sink. 



2. Put into a solution of one per cent, tannin to 

 which enough pyridin is added to clear up the turbidity 

 arising on first mixing. Keep in this for one-quarter 

 hour at 50 C. 



3. Wash several times in distilled water. 



4. Place in a solution of silver nitrate i per cent., 

 to which is added some pyridine ten per cent. Keep 

 at 50 C. for one-quarter hour. 



5. Wash. Reduce with four per cent, pyrogallic 

 acid, to which is added enough pyridine to make the 

 mixture clear. Reduction takes place in a few minutes. 



6. Wash, alcohol, xylol, paraffin. Cut sections. 



7. Double stain with neutral red and methyl 

 blue. 



10. Sp. vespertilionis. In a Tunisian bat, V. kuhli. 

 The infection is sometimes fatal, and relapses occur. 

 The incubation period, after inoculation, is about 

 forty-eight hours. The spirochaete is i2-i8/*. They 

 disappear out of the blood by crisis. 



The spirochaete, according to Gonder, divides 



An. de I' I nst. Pasteur, p. 297, 1907. 



