OF THE TRACHEA IN INSECTS. 
41 
Campcea margaritaria, Ilipparchia Janira, II. Tit /tonus, Pieris napi, and Nootua gamma, 
there are many round glands, each with numerous trachea?. 
In Eristalis and Jlusca the tracheae are as on the stomach, though in the latter the 
systems are particularly large. In hoth, there are several tongue-shaped glands with 
numerous tracheae. In Tipula also are several similar glands. A large trachea enters 
the base of each, and there divides into four or five branches, of which about three con- 
tinue nearly parallel, and give off branchlets from time to time, while the others dive 
to supply the basal part of the gland. In Pentatoma the trachea) resemble those of I 
stomach. 
a 
Male Generative Organs.— Testis. (PI. III. figs. 13, 14, 1G, 18 & 19.) 
In Bombus muscorum, B. terrestris, and B. pratonim, the tracheae generally divide 
dichotomously, but sometimes into three. The end tubules are very long, — a character 
which we often meet with in the testis. In Acheta, Zooms t a, and Gryllns, the air had 
always been removed from the fine ends, which therefore had become invisible. The 
branches were, however, long between the branchlets, and they tapered very little. In 
the pupa of Acheta, the tracheae, so far as they could be seen, resembled those of the 
imago. In Musca the testis is a brown, sausage-shaped body, and the tracheae end in small 
tufts (PL III. fig. 18). In Mristalis the organ is formed on a similar type. The tufts, 
however, though larger, are more open, and consist of fewer branchlets. In Aphrophora 
the tracheae are almost like those of the ganglia. They end in long, gently curved tubules, 
which arise successively, and without forming tufts. 
In the button-like testes of Melolontha long tracheae run from the centre to the 
circumference. They divide three or four times dichotomously, and are very long. 
They, however, diverge but slightly, and are a good deal twisted on themselves. In 
Amphimalla solstitialis they are very similar. . PL III. fig. 16 represents one of the 
least-complicated systems. In Necrophorus mortuorum and N. vespillo the tracheae 
branch simply, small tubules rise from branches of considerable size, and the end tubules 
are straight and of great length. In Carabus the ends of the tracheae had disappeared. 
In Cerambgx moschatus they were much like those of Aphrophora spam aria. In P *a norpa 
the tracheae were almost as in Necrophoms. Most of the ends had disappeared ; and yet 
the fine tubules seemed to be very long, because they remained for a considerable distance 
without any great diminution of size. "When one of the branchlets divided, the two tubules 
were each almost as thick as the branchlet from which they sprang. This character gives 
the tracheae a peculiar appearance, which is very striking. In Pentatoma the testis is 
covered by broad, longitudinal, saccular tracheae, which give off thick branches at the ends 
and sides. 
Vas Deferens. 
This origin is often without tracheae. When they are present, they are often very like 
those on the testis, as for instance in Bombus terrestris, B. muscorum, B. pratonim, Pen- 
tatoma prasina, &c. In Acheta and Locusta it was thin, delicate, and apparently without 
tracheae. In Gryllus, on the contrary, it is large and of a yellow colour. I did not ob- 
VOL. XXIII. 
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