PSYCHE: 
ual fall till death, varied of course in feed- 
ing imagos by slight rises and falls. 
Prof. Engelmann communicates * some 
observations made by Van Lidth de Jeude, 
on the silk glands of the silk worm. 
Each gland beyond the common duct, con- 
sists of a very fine duct, a stout, little con- 
torted, intermediate division (so-called res- 
ervoir), and a long much contorted final 
division; each part has a delicate mem- 
brana propria, andan epithelial layer. The 
inner surface of the duct and beginning of 
the next part have also a firm cuticle. Nu- 
merous fine tracheae penetrate the epithel- 
ium of the middle and end divisions, as do 
also accompanying on independent nerve 
fibres. 
the three portions ; two cells only appear 
The 
nature of the protoplasm of the cells of 
each division is further described at length. 
The silk-gum and the yellow coloring mat- 
ter were found to be secreted by the middle 
The specific peculiarities of the 
silk are developed after the union of the two 
ducts. Silk spun under water was found 
not to differ from that spun in the air, 
thus precluding the idea that drying is 
necessary. 
Concerning the nervous system may first 
be mentioned the papers of Dr. Edouard 
Brandt,** who has undertaken a most com- 
The epithelial cells are diverse in 
in a cross section (more in Cossus). 
division. 
prehensive series of studies on this subject, 
1032 species of hymenoptera, coleoptera, 
hemiptera, lepidoptera, and diptera having 
been examined. ‘The results show: 1. In 
some forms, as in Stylops, the suboesopha- 
45 Carus’ Zool. Anzeig., v.1,p. 100. Original in 
Onderzock. Phys. Labr. Utrecht. 3 R. v. 2, p. 115. 
46 T have not seen the original papers in the 
Hor. Soc. Ent. Ross., vy. 14 and 15. My informa- 
37 
geal ganglion fuses with the next posterior. 
2. ‘*Convolutions” of the brain occur in 
all; but (3) vary in different individuals 
of the same species, and are less developed 
in the males of the social hymenoptera 
4. A 
connection between the development of the 
instincts and that of the brain hemispheres. 
5. The labrum nerves arise from the oeso- 
phageal nerve-ring. 6. When two thora- 
cic ganglia exist, the first corresponds to 
the first or the first two larval ganglia ; 
the second to the one or two thoracic and one 
7. The number of 
ganglia may vary in the same species, e. g., 
bees and wasps. 
lion may be compound instead of the ulti- 
mate one. 9. Bombus and Tenthredo have 
a thoracic sympathetic system like that of 
the abdomen. 10. The resolution of one lar- 
val ganglion into a number in the adult may 
occur, as in Volucella. 11. In cases of a 
single ganglion in the thorax of hemiptera, 
this corresponds to the last two thoracic 
and all the abdominal ganglia. 12. Lepi- 
doptera have four abdominal and either 
two or three thoracic ganglia. 
Mr. N. M. Wagner” points out the 
supra-oesophageal ganglion as the seat of 
almost all the functions of the cerebral 
hemispheres of the vertebrates, and it, in 
correlation, has a more complex structure 
than the succeeding ganglia, though formed 
on the same plan. Nerve cells occupy the 
periphery, and fibres the interior ; towards 
the centre are three groups of small cells 
one above the other, and connected by a 
than in the females and workers. 
abdominal ganglia. 
8. The penultimate gang- 
tion is taken from the Journ. Roy. Micr. Soc., v. 
2, p. 863. See also Comptes Rend., v. 89, p. 475. 
47 Comptes rend., 1879, p.378. Ann. Mag. Nat. 
Hist., Nov. 1879, p. 398. 
