1002 General Notes. [ October, 
given us a résumé of his memoir. He first studied the tissues of 
the larva and of the imago, and then followed out the mode of 
destruction of the larval tissues and the mode of genesis of those 
of the perfect insect. In his researches upon the nervous system 
of insects he found that besides the ganglionic chain and the 
stomato-gastric system, certain insects possessed nervous ganglia 
under the integuments, in some cases distributed without appa- 
rent order, but in others grouped symmetrically and connected 
with the principal centers. Another discovery was, that the sen- 
cells. Thus every part of the tegument has general sensibility. 
It has long been recognized that some of the hairs, or hollow 
conical outgrowths of the chitinous cuticle secreted by the hypo- 
erm, were special organs of touch, and were accompanied by a 
nerve which formed a ganglionic bipolar enlargement. M. Vial- 
lanes has proved that the hair is secreted by a specially modified 
hypodermic cell, and that in the protoplasm of this cell the ter- 
minal prolongation of the bipolar nervous cell ends. The dorsal 
vessel of an insect is formed of a single layer of cells, but each 
cell is contractile through the presence in it of striated muscular 
microscopic fibrils. Each of these fibrils begins and ends in a 
small disc. A theory, generally admitted, holds that the active 
unity of a muscular fibril must be the space between two small 
discs, but this is the first verification of the theory. 
__ The voluntary muscles of vertebrates exhibit little variety even 
in different zodlogical groups, and in any species have the same 
structure throughout. But in insects the motor muscles of the 
wings differ from those of the legs, and the contractile tissue of 
‘the larva from that of the adult. In the muscles of the wings of 
a fly the fibers (faisceaux) have no sarcolemma and only a few 
fibrils (colonnettes) ; in those of the wing of Dytiscus the fibers. 
have no sarcolemma and only a single colonette or fibril, while in 
those of the legs the single fiber is enveloped in a sarcolemma. 
_ The ultimate elements, however, are the same in all. Previous . 
Ahistologists had proved that the motor nerves of the muscles of 
the legs of insects separate into their constituent fibrils imme- 
diately after penetrating the sarcolemma, but M. Viallanes shows 
that in insect muscles consisting of several fibers the nerve 
__ branches like a tree, as it does in vertebrates, while it separates at 
= es into its constituent fibrils in muscles formed of but one 
The second part of the memoir of M. Viallanes treats of the 
ruction of the larval tissues. M. Weismann had proved that 
muscles, tracheze, adipose bodies and peripheric nerves of the 
‘entirely during the metamorphosis. M. Viallanes 
