22 BULLETIN 817, U. S. DEPT. OF AGRICULTURE. 
when cut but cutting with difficulty, indicating a beginning indura- 
tion. ; 
The lesions in the lungs are more striking macroscopically than 
those in the liver. In our mildest cases there were small bright-red 
hemorrhagic spots, in which the larve usually could be discovered 
without difficulty. As a rule the lungs were more or less edematous. 
The small bright-red petechial hemorrhages and edema are very 
characteristic of Ascaris invasion and differentiate it from other 
conditions that are likely to be seen in the lungs of pigs. In more 
Fic. 5.—Ascaris suum. Larva in section of lung of mouse 1 week after infection. 
Photomicrograph. Highly magnified. 
severe cases there were ecchymotic patches of considerable size, giv- 
ing the lung a spotted appearance. Im still more severe cases an 
entire lobe of the lung was involved, and in the worst cases both 
lungs were greatly swollen, edematous, intensely hemorrhagic, the 
color of liver, and extensively hepatized. Microscopically the path- 
ological picture varied from that of an acute lobular pneumonia in 
which the areas of inflammation centered around the bronchioles to 
lobar pneumonia in the stage of red hepatization. The accompany- 
ing photomicrograph (figure 5) shows a section of the lung of a 
mouse with a larva in situ 7 days after ingestion of Ascaris swum 
eggs. In portions of the section will be noted areas of consolidation, 
