PROTOZOA 409 



bodies of the insects and that the eggs may be infected and may 

 carry the organisms. 



The spirochaetes stain in smear preparations with Giem- 

 sa's stain. They do not stain in sections of tissue with the 

 ordinary staining methods. Levaditi 's 3 method is highly 

 recommended for staining these bodies. 



The fresh tissue is cut into small pieces which should not be 

 thicker than 2 to 4 millimeters. 



Fix in ten-per-cent formalin (four per cent formaldehyde) for 

 twenty-four hours. 



Wash in water. 



Dehydrate in 96-per-cent alcohol twenty-four hours. 



Wash in water. 



Place in a 3-per-cent silver-nitrate solution at incubator tempera- 

 ture (37.5 C.) and in the dark for three to five days. 



Wash in water for a short time. 



Place in the following solution (freshly prepared) : 



Pyrogallic acid 2-4 grams. 



Formalin 5 cc. 



Distilled water 100 cc. 



Leave in this for twenty-four to forty-eight hours at room tem- 

 perature. 



Wash in water. 



Dehydrate in graded alcohols. 



Embed in paraffin and cut thin sections. 



The sections may be examined without further staining, or, if 

 desired, may be weakly counterstained with Giemsa's solution or 

 hematoxylin. 



There are several other methods for demonstrating these 

 organisms. 



A disease of the pig due to spirochaetes. Dodd 4 has re- 

 cently described a spirochaete which he found in a pig sent to 

 the government laboratory in Pretoria. The examination 

 showed very few morbid changes in the tissues but the skin 

 was sprinkled with dark, hemorrhagic-like spots. From scrap- 

 ings of these lesions he was able to find the organism. It is 



3 Levaditi. Compt. rendu de la Soc. de Biol., Vol. LVIII (1906) 

 p. 67. 



* Dodd. A disease of the pig, due to spirochaeta. Jour. Comp. 

 Path, and Therap., Vol. XIX (1906) p. 216. 



