1885. | Entomology. 79 
to follow the tracheal branchings. Each stem forming the axis 
of a column, divides racemosely into branches, and each branch 
bifurcates into a pair of capillaries whose walls are perfectly 
smooth. 
On the application of osmic acid to the abdomen of the living 
insect, death does not follow immediately, but the luminosity is 
continued for atime steadily. Long before the animal has ceased 
to move, the luminous plates begin to grow brown, the change 
proceeding from the anterior part, from the place where the 
trachee enter. The brown color becomes concentrated in round 
fields corresponding to the vertical columns, each surrounded by 
a circle of light. 
The terminations of the vertical tracheal stems are enclosed in 
cylindrical lobular masses, the columns of the luminous organ, 
the trachee sending out its racemose branches within each 
column; in macerated specimens (by osmic acid and thymol) 
dark masses are seen where the branches bifurcate to form the 
capillaries; the cells of which the columns consist exhibit no 
nuclei. [Judging from these figures it would seem as if the dark 
spots represented the nuclei: if this be the case every tracheal 
branch is in a cell and its place of bifurcation at the cell-nucleus.] 
Emery finds no case of the anastomosing of the tracheal capil- 
laries either of the same or of different stems; he is satisfied that 
no such anastomosing occurs in Luciola. His view is opposed to 
that of Kölliker and of Wielowiejski on Lampyris. [The con- 
clusion of Wielowiejski appears to be without sufficient founda- 
tion; his figures show only a casual collection of a few of the 
intricately twining tubules. 
The cylindrical lobes or columns of the luminous organ are 
separated from each other by a granulated substance, and the 
tracheal capillaries extend to this and to the granulated paren- 
chyme-cells, penetrating between the cells but not entering them. 
The dorsal fat-layer was examined for the purpose of establish- 
ing homologies. It is white, has urate concretions swimming in 
the plasma of its cells, which are {not distinctly limited by cell 
walls; but it has nuclei like those of the parenchyme of the 
luminous organ; and these facts as well as the tracheal arrange- 
ments favor the view that the luminous parenchyme is derived 
from the fat-body. It cannot be that the latter with its urate 
concretions is the result of combustion in the luminous organ, 
for the tracheal arrangements negative such a view. 
In comparing Lampyris, Emery concludes that M. Schultze’s 
tracheal end-cells are represented in Luciola by the bright cell- 
elements of the luminous cylinders enclosing the tracheal stems ;. 
that the tracheal branching is similar; also that the reactions are 
the same, csmium being precipitated so as to darken the sub- 
stance in both cases. In Luciola there is a higher differentiation 
of parts. : 
