426 
TasLp 3—.Continuea 
INDIANAPOLIS, IND. 
: : = kK os 
= S co) ; o| & 
eb eae é || sacle 
Sl eal ee (ue deret elie ta ed a eel ees o/s] Ss 
Ser ete |e) 8) el) sie! a) 2] Ss | ota 
H|S\|B/S/a/2/4/5]<4|21/0/4/A]< 
| 
Relative humidity (percentage)...| 21 | 79 | 77 | 73 | 66 | 67 | 68 | 65 | 67 | 68 | 68 | 73 | 77 | 71 
Sunshine (percentage).........-.-.- 12 | 41 | 47 | 40 | 51 | 53 | 62 | 68 | 63 | 66 | 61 | 52 | 40 | 54 
Average hourly wind velocity (in 
MTLTLOS) Metciee Nee oop cle cheaters rene bates 12 |11.7)11.5 Thee 9.9} 8.9} 8.2] 7.4| 8.3] 9.4/10.4]11.5]10.0 
During the pericd Noy.—June, the level of the pond is not rapidly re- 
duced. September and October are on the average the dryest months of the 
year. July and August are the hottest. It is during this period (July— 
Oct.) that the level is reduced most rapidly and the stress on the organisms 
is most acute. In this period occurs the minimum precipitation, lowest rela- 
tive humidity and smallest number of rainy days (i. e., .O1 inch or more pre- 
cipitation), the maximum temperature and the greatest sunshine per- 
centage. All of these factors tend to reduce the level of ponds by evapora- 
tion. The lower wind velocity tends to reduce the evaporation to a slight 
degree. 
The amount of stress produced by a reduction of the level varies in 
different years. In thirteen years of precipitation records for Blooming: 
ton, the minimum for four months, July—October, was in 1908. The mayi 
mum occurred in 1896. In 1908 the amount of precipitation for the foui 
months was 4.99 inches. In 1896 the maximum was 20.78 inches. The 
average for the entire thirteen years for these months was 12.66 inches. 
To state it another way: the minimum for this period was 39+% of the 
average and 23.54+% of the maximum. That is, between four and five times 
as much rain fell during this period of one year as fell during the same 
period of another year. This irregularity, more than any other factor, 
prevents the fauna of this pond and all small solution ponds from becom- 
ing even relatively static. In the larger ponds the effect is less acute. 
The drying up of the pond in ’OS killed all the amphibian larvie, the 
corethra larvee and caused the emigration of some of the aquatic beetles. 
