20 THE DISPEESIOX OF THE GIPSY MOTH. 
on the screens as a result of this liberation. When the experiments 
were started it was planned to examine thoroughly a few willow 
sprouts, which were growing along the race track not far from the 
water tower, but on account of the pressure of other work this was 
neglected. In making an examination of the screens May 28 it was 
found that several old egg clusters and a considerable number of 
caterpillars were present on a clump of willow sprouts about 25 feet 
from the screen on the west side of the tower. In spite of this, how- 
ever, no caterpillars were found on this screen during the season. 
There is a bare possibility that the caterpillar found on the screen 
on the opposite side of the tower may have come from some of the>e 
willow sprouts, but it is doubtful whether this is the case. The 
screens were removed June 13 and examined at the laboratory in 
i he same manner as those already mentioned, but no other cater- 
pillars were found. 
The foregoing experiments were carried on under natural condi- 
tions and on a large scale, and in addition two other test^ were made 
by Mr. Mosher. One large screen was built in the form of a ero:— . 
the same as the one placed on the tower at Mount Gilead. It was set 
up on land at Manchester. Mass.. where the forest had recently been cut. 
Large trees surrounding this area were badly infested with the gipsy 
moth, and some additional data would probably have been secured 
from this experiment if a forest fire had not run through the area 
where it was conducted. 
Another raft was constructed at Chebacco Lake in Essex. Mass.. 
similar to the one used at Sandy Pond, but owing to bad weather and 
high winds it was impossible to anchor it securely in the center of 
the lake until it was too late to secure the data desired in the experi- 
ment. Before these tests had been carried very far it appeared 
desirable to check up the results in a more definite way. and in order 
to do this a series of experiments were planned, which were carried 
on by Mr. C. W. Collins and the writer on the salt marshes (PL IX) 
between Lynn and Severe. Mass. 
EXPERIMENTS ON LYNN MARSHES. MASS. 
A box of egg clusters containing many newly hatched larva- was 
attached to the top of a pole about 6 feet from the ground. This 
point was used as a central station and was half a mile or move from 
any tree or tree growth. One end of the box (PL IX. fig. 1). con- 
taining the egg clusters and caterpillars, was partly cut away with a 
knife, while in the other a small hole was made to allow the wind to 
blow through the bpx. Small screens. 2 feet wide and G to 8 feet 
long (PL X), were attached to stakes which were sharpened so that 
they could be pressed into the ground; so that when these screens 
were set up they were about 5 feet above the ground. They were 
