368 BIOLOGY OF THE LABORATORY MOUSE 



They would shun food placed before them. The stools of the infected 

 animals were soft and mucoid. He found clumps of the adult worms in the 

 intestine usually pinned to the mucosa for considerable depths. Porter (29) 

 found that death of heavily infected animals was due to lobar pneumonia 

 resulting from the migration of the larvae through the lungs similar to that 

 produced by A scar is larvae. He states that in cases of mild infection macro- 

 scopically the lungs show small haemorrhagic areas in which the larvae can 

 usually be found, while in severe cases the lungs may be entirely haemor- 

 rhagic, congested, and edematous. Microscopically there appear areas of 

 marked consolidation and diffuse haemorrhage. 



A compensatory emphysema may be seen in areas in proximity to the 

 migrating larvae. Deposits of pigment were found near the larvae, usually 

 free, but sometimes within the mononuclear leucocytes. He observed that 

 in the intestine the worms migrate extensively in and out among the 

 vilH, causing local destruction and shrinking of the tissue, and hinted 

 that the adults may feed upon the glandular secretion or tissues of the 

 host. 



A period of at least 5 or 6 days after the egg is passed from the host is 

 required for the infective larva to develop. Thus, it is quite unlikely that 

 heavy infection with this parasite would occur among laboratory animals 

 if the cages are frequently cleaned. 



Protospirura muris (gmelin, 1790). — This species of Spiruridae infests 

 the stomach of mice and rats. It apparently occurs commonly, and often in 

 large numbers. Hall (17) states that he has seen a case in which the empty 

 stomach was distended by a number of these worms which ballooned the 

 stomach walls as so many clock springs might have done. The parasite is 

 quite cosmopohtan in its distribution. 



These are rather thick worms with relatively small heads. The males 

 are from 14 to 28 mm. long with a maximum diameter of over i mm., and the 

 females are 15 to 40 mm. long with a maximum diameter of 1.75 mm. As 

 with other Filarioidea, an intermediate host is employed in the Hfe cycle, the 

 eggs developing into infective larvae in the body of the meal worm, Tenehrio. 

 Thus, control measures should be directed toward the eradication of meal 

 worms. 



Gongylonema neoplasticum (fibiger and ditlevsen, 1914). — Also 

 known as Spiroptera neoplastica. This Spiruridae, which has been reported 

 from Denmark, the Danish West Indies, and the United States, occurs in the 

 squamous-celled anterior portion of the digestive tract of the mouse and rat. 

 Insects including the cockroach and Tenebrio serve as intermediate hosts. 



