You may be looking at one 
of these discs, still in position 
on the leaf, when suddenly it 
separates and drops to the 
ground. This is the act of 
the contained grub, but how 
accomplished has not yet been 
discovered. The disc falls to 
the ground, and if it has 
alighted upon an unsatisfactory 
spot it begins to set up those 
jerking movements already 
mentioned. Judging from the 
fact that the way to induce 
the movements is to expose the 
disc to strong sunlight, they 
appear to be a provision against 
the grub getting dried up. It 
Marvels of the Universe 1041 
Photo bu] (7. Main, PES. 
THE SEPARATED DISC. 
Both upper and lower sides of the disc are here shown, enlarged to six times the 
natural size. The first figure shows the upper side, the second the lower or silken 
side. The larya shows through. 
seeks a shady position, where it can lie safely all through the autumn and winter. In spring it 
changes to a chrysalis in its cell, and, later, when the Maple and Sycamore are in leaf, a four- 
winged Saw-fly emerges and sets about providing for the continuance of the race. 
SEA SQUIRTS 
BY J. SINEL- 
Down at the lowest limit to which the tide recedes, on every rocky shore, wherever blocks of 
stone are supported on others at some little distance from the eround, so as to form little 
grottos, or where portions of 
rock project as overhanging 
ledges, the observant visitor 
will not fail to have noticed, 
close packed on the under 
side of the roofs thus formed, 
masses of globular leathery 
bodies which, in size, colour 
and shape somewhat resemble 
good-sized cranberries and 
which, when touched, emit 
little jets of water. 
These, in popular nomencla- 
ture are the Red Currant Sea 
Squirts (page 1042). If not 
actually the most abundant, 
they are at least the best 
known of that strange class of 
animals which forms the sub- 
ject of this article. They are 
classed as Tunicata, because 
they are invested with a 
Photo bu} [He Main, PES. 
THE MAPLE-LEAF CUTTER. 
The upper and lower sides of the larva are here shown about six times the 
natural size. 
