20, 6 Schwartz: Ascaris vitolorum 665 
perimental animals, whereas after feeding fully virulent eggs 
the feeces of the host animal seldom contained embryonated eggs. 
Exposure of eggs to tropical sunlight in order to determine 
the effects of light and heat on the viability of the embryos 
resulted in the hatching of a number of eggs, as evidenced 
by the finding of free larve and empty eggshells after ex- 
posure. Since embryos inclosed in eggshells are stimulated to 
increased activity under the influence of heat, it may be con- 
cluded that the excessive activities to which they were subjected 
during the exposure resulted in their liberation from the shells. 
EFFECTS OF DRYING AND OF TROPICAL SUNSHINE ON EMBRYONATED 
EGGS 
The eggs of Ascaris vitolorum are resistant to drying. Eggs 
were allowed to dry on slides that were kept in shaded places 
for various periods ranging from several hours to several days, 
and after being moistened with water they frequently resumed 
their sluggish movements without further stimulation. In cases 
in which the embryos showed no movements after being 
moistened, they were readily stimulated to activity by heat. 
Eggs similarly exposed on slides to the influence of the sun’s 
rays did not recover after an exposure of one hour. Micro- 
scopic examination showed these eggs to be paler than normal 
eggs and also revealed evidence of internal disorganization of 
the larvee. 
Further studies on the effects of sunshine on embryonated 
eggs were made by exposing beakers containing them to sunlight 
for various periods. The minimum exposure of one hour was 
invariably destructive to eggs on bright days. After exposure, 
the eggs were examined under a cover glass. They were not 
only pale in appearance, but also showed profound internal dis- 
organization and vacuolization, the outline of the embryos being 
rather hazy and the contents opaque. 
In order to determine the effects of light and heat separately, 
several lots of eggs were exposed in vials, some of which were 
painted black with India ink, thus shutting out light. <A one- 
hour exposure proved fatal in both blackened and unblackened 
vials, thus showing that the exclusion of light did not diminish 
the lethal action of heat. 
The vials and beakers used in these experiments were placed 
on the ground outside of the laboratory, and a thermometer . 
was placed close to the glass containers. The thermometer 
usually registered 45° C. 
