LIFE HISTORY OF ASCARIS LUMBRICOIDES. 29: 
young pigs are exposed, would go far toward reducing the losses from 
pheumonia. 
LONGEVITY OF LARVZ OUTSIDE THE HOST. 
Stewart (1916a) noted that the newly hatched larvee eliminated — 
in the feces of rats recently fed the eggs of Ascaris lwmbricoides ° 
might survive for three days. He found, further, that larve that © 
had passed through the lungs and reached the large intestine of 
mice if placed in tap water were alive and active at the end of two 
hours, but were dead at the end of 24 hours. Larvee from the lungs’ 
of a rabbit that died 10 days after feeding with the eggs of ‘Ascaris | 
suum have been kept alive in physiological salt solution by the © 
writers for 18 days (Experiment No. 16). 
The survival of larvee as long as 13 days after their removal from | 
the host would seem to offer some support to Stewart’s rat and 
mouse theory, but the fact that they are so slightly resistant to un- 
favorable conditions, such as dryness, and as observed by ‘Stewart 
may not live as long as 24 hours in tap water, is evidence very much 
against Stewart’s suggestion as to the spread of Ascaris larvee from 
rats and mice to human beings or pigs. It is known that adults re- 
moved from the intestine of their host can be kept alive for ccn- 
siderable periods of time. For example, Hall (1917) found that they 
may survive removal from their host as long as 26 days if kept in 
Kronecker’s solution. Many species of parasitic nematodes can 
thus be kept alive with careful handling after removal from their 
host. The survival of Ascaris larve for a time if kept in physiolog- 
ical salt solution after they have been removed from a host animal 
is therefore a phenomenon not unusual among parasitic nematodes, 
and can not be considered as indicating the probability, under natural 
conditions, of the passage of the larve from one host to another and 
the resultant infection of the latter. 
NATURAL OCCURRENCE OF ASCARIS IN SHEEP. 
Sheep are occasionally found to be infested with Ascaris. Ru- 
dolphi (1819, p. 49) mentions under the name of Ascaris ovis a 
specimen in the collections of the Vienna Museum. Diesing (1851) and 
von Drasche (1883) give descriptions of this specimen, and the latter 
also describes two badly preserved specimens of Ascaris found in 
a sheep by Koebel. Copeman (1842) found 25 ascarids in a lamb. 
Neumann (1884) found several specimens of Ascaris in sheep. In 
the collections of the Bureau of Animal Industry are specimens of 
Ascaris collected from sheep at Brookings, S. Dak., Blairsville, Pa., 
and Bethesda, Md. Apparently in no case has a fully developed 
female Ascaris containing well-formed eggs been found in sheep. 
