156 Miscellaneous. 
meter, and are filled with a yellowish fluid, and a fine purplish gra- 
nular matter, which in mass gives them a dark purple colour, and 
which, in the aggregate of the cells, gives the glands a very deep pur- 
ple or almost black colour. When the cells are compressed, or the 
contents pressed out, the granules exhibit lively molecular movement. 
In the centre of the mass of granular matter of the cell, and only 
seen upon compressing the latter, is a round, translucent nucleus, 
measuring the 1-5000th inch in diameter, and containing a minute 
refractive nucleolus. 
The secreting cells vary in colour in different insects, and in the ag- 
gregate give the colour to the glandular bodies. The reservoir also is 
lined with cells. In Upis Pennsylvanica they are brownish, or nearly 
colourless, measure the 1-750th inch in diameter, contain some finely 
granular brownish matter, and a large round or oval translucent, 
faintly granular nucleus, measuring 1-1250th inch, with a large, 
round or oval nucleolus 1-2727th inch in diameter. 
The secretion of the glands of Julus marginatus, contained within 
the interior of the body, is deep yellow in colour, and contains a few 
of the purplish granules of the cells. It resembles oil in consistence, 
but is soluble in water and alcohol. It is neither acid nor alkaline ; 
evaporates at a temperature of 250° F., without residue ; is acrid to 
the tongue, Schneiderian membrane, and conjunctiva; smells like hy- 
driodic acid, and stains the cuticle brown. The last two properties 
led me to suspect the existence of iodine, but the usual reagents pre- 
sented none. It probably belongs to a class of peculiar organic com- 
pounds, found in the odoriferous principles of animals, not yet in- 
vestigated. 
Exteriorly the reservoirs of the odoriferous glands of insects are 
furnished with transverse muscular bands of a brownish colour, about 
1-1578th inch in breadth, and separated by wide intervals. 
In Julus the body of the glands possesses no distinct muscular 
bands, but the neck is provided with them.—Proceedings of the Aca- 
demy of Natural Sciences of Philadelphia, vol. iv. p. 234. 
JOURNEY TO EXPLORE THE NATURAL HISTORY OF SOUTH AMERICA. 
To the Editors of the Annals of Natural History. 
GENTLEMEN, 24 Bloomsbury Street, Jan. 19, 1850. 
In the January Number of your valuable Magazine for 1849, you 
were good enough to insert extracts from a letter I had received from 
Messrs. Wallace and Bates, two gentlemen who are investigating the 
Natural History of the Amazon River and its tributaries in South 
America, and who consign their collections to me for sale. I now 
send you extracts from a letter just received from Mr. Wallace, dated 
Sautarem, Sept. 12, 1849, which, if you think sufficiently interesting, 
you may perhaps feel inclined to insert :— 
“T have got thus far up the river, and take the opportunity of 
sending youa few lines. To come here, though such a short distance, 
took me a month. I am now waiting here to get to Montalegre, but 
the difficulties of getting men even for a few days are very great. Here 
