364 
Transactions of the Society. 
Dr. Keilin has located ten pairs of vestigial spiracles, and he 
says none of them is in any way functional. 
We cannot ignore this evidence as to the possibility of the 
coat being impervious, which, if definitely established, excludes 
the suggestion of the integument acting as a respiratory organ. 
At the same time it opens up the question as to the methods em- 
ployed by the larva in obtaining its supply of air. 
Both Dr. Miner t and Frankenberg have remarked on the rapid 
filling of the air sacs and tracheal system with air, within a few 
minutes after hatching of the larva. 
Frankenberg’s experiments on newly-hatched larvae are most 
interesting. Shortly reviewed they are as follows : — 
Immediately on leaving the egg neither the four sacs, or 
tracheal tubes connecting them, contain air, but are filled with a 
fluid which is somewhat more highly refractive than water. The 
ultimate filling of the sacs with air usually takes place in five 
minutes from release from the egg. The caudal ends of the 
tracheal tubes and posterior sacs fill first, the air can then be seen 
to shoot forward into the main tracheal stem from the tenth to the 
third segments. The thoracic sacs then fill. Almost immediately 
the air disappears, apparently absorbed by the blood. 
He then proceeds to carry out the following simple experi- 
ments : — 
Head Cut Off shortly befoi'e Filling . — Immediately the posterior 
sacs fill, then the thoracic pair, in the normal manner throughout. 
Larva Cut in Half in the Middle . — Shortly after, a regular 
filling of the posterior sacs ; the thoracic remain empty. This 
experiment was repeated with the same result. 
Body Cut Through close behind the Posterior Sacs . — Neither the 
posterior nor anterior filled. 
One cannot help but admit some kind of gas glands which 
must lie in the eleventh segment. 
The morphological examination shows nothing more advanced 
than a network of globular cells which accompany the tracheal 
main stem a short distance. The larva being confined in water 
under a cover-glass, it has no meaiis of communication with 
atmospheric air. 
According to these experiments, an active secretion of gas 
■cannot be doubted. 
Frankenberg’s paper (10) is in German, and consists of ninety- 
five pages, from which we have taken a few extracts contained in 
some rough translations of portions of his important communi- 
cation. We are, therefore, not able to draw so fully from his paper 
as we should have liked. 
W e have seen that the newly-hatched Curethra has been able to 
fill its sacs under a cover-glass in an apparently limited amount 
•of water. We cannot do better than refer to Arber’s statement as 
