328 
Psyche 
[December 
and would not rest on the skin except very momentarily, 
but kept up a continual dashing about in the tube. The 
larvae were all protruding from the egg shells, but the swift 
movements of the fly seemed to prevent them from remain- 
ing on the skin for a sufficient length of time to allow them 
to crawl from the shells. This continued for about five 
minutes, and it was then noticed, with the aid of a hand 
lens, that as the fly dashed against the side of the tube one 
of the larvae was left hanging to the glass. About one 
minute later this was repeated and a second larva was left 
crawling about on the inside of the tube. The fly was then 
removed and the two small larvae inside the tube were 
picked up on the point of a needle and gently placed on my 
left forearm at about the upper third of the median flexor 
region. Since there were no abrasions of the skin at this 
area, an opportunity was given for observing the entrance 
of the larvae into unbroken skin. 
The two larvae were placed in the skin slightly less than 
an inch apart, and each remained at exactly the site where 
it was placed. Neither of them could be detected as having 
moved even a quarter of an inch. They remained so 
motionless that at first it was feared that they had been 
injured by the needle in transferring them from the tube 
to my arm. After watching them closely with a 10 X lens 
for a few minutes, however, a few faint contractions could 
be seen, and it was also noted that the anterior, or larger, 
end of each larva seemed to be sinking very slowly into 
the skin. This large end of each larva seemed to be about 
one-third, horizontally, pressed into the skin, and was evi- 
dently securing traction through the use of the oral hooks 
and dermal spines, while the posterior end exerted a pro- 
gressive forward motion. The larvae were lying nearly 
parallel with the skin, and with but a slight arching near 
the posterior end, so that their position in relation to the 
skin surface was thus very oblique, and the penetration 
was at first beneath just the outer part of the skin. 
One of the larvae had practically all of its large anterior 
part imbedded in the skin in about thirty minutes. It was 
then able to obtain sufficient purchase with its spines, so 
that rapid progress was made and the posterior end was 
soon inside. At the end of 42 minutes from the time this 
