SCIENTIFIC SUMMARY. 
339 
some silk-worm eggs from Japan, and are willing to distribute a portion of 
tbe same to other societies, also to private individuals, who can satisfy the 
Society that they have a sufficient quantity of mulberry leaf of their own 
growing to sustain the worms properly. It is hoped that the attention of 
colonists will be given to propagating the mulberry. 
The Ovipositor in Spring-tails and their Kindred. — Mr. L. S. Packard 
describes, among other structures, one of the above, which is rather novel. 
He is disposed to consider it an ovipositor. In the genus Achorutes it may 
be found in the segment just behind the spring-bearing segment, and 
, situated on the median line of the body. It consists of two squarish valves, 
from between which project a pair of minute tubercles, or blades, with four 
rounded teeth on the under side. This pair of infinitesimal saws remind 
one of the blades of the saw-fly, and he is at a loss what their use can be, 
unless to cut and pierce so as to scoop out a place in which to deposit an 
egg. It is homologous in situation with the middle pair of blades which 
compose the ovipositor of higher insects, and if it should prove to be used 
by the creature in laying its eggs, we should then have with the spring an 
additional point of resemblance to the Neuroptera and higher insects, and 
instead of this spring being an important differential character, separating 
the Thysanura from other insects, it binds them still closer, though still 
differing greatly in representing only a part of the ovipositor of the higher 
insects. 
The Tarsi of Dytiscus. — In a very important paper on this subject, by Mr. 
B. T. Lowne, M.R.C.S., in the u Monthly Microscopical Journal” for June, 
there are some interesting statements. It says that there are about 200 disk- 
bearing hairs on the anterior dilated tarsus of Dytiscus marginatus, punctulatus, 
or circumjlexus , the three common British species. T,wo of the disks on each 
tarsus are of remarkable size, and differ in several points beside size from the 
remainder. The largest of the large disks is situated on the posterior portion 
of the proximal tarsal joint, close to the tibia, and usually measures — th of 
an inch in diameter. The smaller is about half this diameter, and is situated 
in front of the larger. The other disks cover the remainder of the dilated 
portion of the tarsus, and are not more than about jl^th of an inch in dia- 
meter. The middle pair of tarsi have their under side clothed with a dense 
pad of disk-bearing hairs similar to the latter. If the integument of the 
upper surface of one of the anterior dilated tarsi be carefully removed, the 
cavity of the tarsus will be found to be occupied, in great part, by a large 
but delicate sac. The main trachea with its sacculus and the tendon of the 
last tarsal joint will be seen lying upon it, and these occupy all the remain- 
ing space in the cavity of the tarsus. The sac will be found full of a gela- 
tinous viscid substance, the same as that which exudes from the hairs. It 
is well supplied with tracheal vessels from the main tracheal trunk, indicat- 
ing that it is an active secreting gland. If a portion of the upper part of 
the sac be removed, and its contents cleared away with a camel’s-hair 
pencil, the internal orifices of the disk-bearing hairs of the pulvillus will be 
seen distinctly in the centre of nipple-shaped projections of the integument 
which project into the sac. 
The Oyster Culture. — A valuable report on the present efforts in this 
direction will be found in the “ Journal of the Society of Arts,” May 5. 
