311 
Class I, Swamps.—The swamps studied are of a type common in the 
southern end of the state. Most of them are grown up to cattail, the 
density of which will be realized by reference to Fig. 1 and 2. The 
water generally contains a great deal of decayed organic matter. Around 
the edges usually, and in the main channels (if there are any), the water 
is clearer. At Carbondale the railroad shops, round-house, and yards 
are in a series of these swamps (Nos. 54-57, 59, 61). The physicians 
in town have all spoken to me of the large number of cases of malaria 
among the railroad men, and I do not doubt that these swamps are partly 
responsible. 
Class II, Marshes—A marsh, as the term is here used, is not as 
deep as a swamp, does not contain so much organic matter, and con- 
tains a considerable growth of grass besides some cattails. In Carbon- 
dale such a place (No. 71) is found opposite the old cemetery near the 
negro school. This place (Fig. 3) produced many malarial mosquitoes. 
Class III, Ponds——The ponds at Carbondale are -small bodies of 
water artificially formed. No. 58* in the A. & L. Tie Company’s yards 
and their two “creosote lakes” (Nos. 66 and 67), No. 52 on Chestnut 
street, No. 45 east of Freeman street, and the pond on the campus of the 
State Normal School (No. 179) are examples. The growth in these 
ponds varies from none at all, as in the Tie Plant property, to that of a 
swamp. ms 
Class IV, Roadside Ditches—Especially along built roads there are 
often left ditches which contain water and are grown up to grass or cat- 
tail. Numbers 62 and 63*, near the Illinois Central yard office, are types. 
Many other ditches show no growth at all and, as will afterwards be 
shown, yield comparatively small numbers of mosquitoes. 
Class V, Creeks and Streams—Crab Orchard Creek and its tribu- 
taries, Pyles Fork and a creek (No. 53) running into the swamps north 
of town, are those which I watched most closely. 
Class VI, Open Drains through Towns (Fig. 4, 5, 6, 7)—These 
drains may originally have been natural streams, but in the case of the 
two watched at Carbondale (Nos. 47 and 48), their courses have been 
somewhat altered. 
Class VII, Lakes—Thompson’s Lake (No. 51, Table A) at the south 
edge of town is leased by the Country Club and is consequently much 
visited by many of the residents. It is also important because of its 
proximity to town. 
Mosquito-producing Factors of Various Types—While all of these 
kinds of breeding-places yielded Anopheles, it soon became apparent that 
some were much more productive than others. 
The cattail swamps might be supposed, from their large area, to breed 
more malarial mosquitoes than any other waters, and they are no doubt 
important, although they present certain features which seem to decrease 
the output. I have found some of them yielding these mosquitoes in 
~~ * No. missing on map. (Continued on p. 317.] 
