ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
349 
the small transparent colonies of the typhoid bacillus on the first plate 
are easily distinguishable in 20 hours under the Microscope. On the 
second plate, after 36 hours the typhoid colonies are yellowish, with 
markedly irregular margins, while the coli colonies are still round. 
Keeping Mosquitoes alive. — Dr. Bancroft * has found that mosquitoes 
can be kept alive, after feeding once on human blood, by suspending a 
banana in the vessel in which the insects are confined. The banana 
should have the skin partially removed, and be renewed every fourth or 
fifth day. In this way the insects can be kept alive for upwards of six 
w’eeks. This fact may be useful to those experimenting with mosquitoes 
and blood parasites. 
Mr. C. Y. Creagh f states that he has kept mosquitoes alive and well 
by feeding them on a mixture of sherry and sugar. The mixture con- 
sisted of about a saltspoonful of dry sherry and an equal quantity of 
brown sugar, and was changed every 2 or 3 days. A small quantity of 
water should also be supplied. An inverted finger-glass, placed on 
coarse flannel to afford ventilation, forms a good cage. 
Gasometer for Fermentation Tubes. :£ — The apparatus (fig. 94), 
devised by Mr. W. D. Frost, consists of a piece of triple-plated tin, cut 
in the shape indicated, about 8 in. long, 6 in. wide at one end, and 2 in. 
Fig. 94. 
at the other. About 1/2 in. of the upper edge is bent over at a right 
angle. The lines are ruled in with ink, and then the surface is brushed 
over with shellac. The perpendicular lines are about 1 cm. apart, and 
the nine radiating lines divide these into ten equal segments. The 
* Brit. Med. Journ., 1899, i. p. 828. f Tom. cit., p. 1062. 
t Journ. Applied Microscopy, ii. (1899) pp. 263-4 (1 fig.). 
