1979] McCluskey & Soong — Rhythm Variables in Ants 93 
The third, POSITION, was calculated as (.80 X total no. out - no. in 
tube)/(total no. out - no. in hot half of arena). It is an index of how 
far out into the warm (i.e., nearest) half of the arena one would have 
to go to encompass 80% of the ants which were out of the nest at the 
time (50% would not work, because too often the 50% line was 
down in the tube rather than out in the arena). This position assay 
may be illustrated by sample calculations: If all the ants were in the 
warm half of the arena, the 80% point would be 80% of the way out 
through the warm half. If 20% were in the warm half and 80% in the 
tube, the 80% point would be 0% of the way through the warm half. 
If 80% were in the warm half and 20% in the hot half, the 80% point 
would be 100% of the way out through the warm half. 
The fourth, ACTIVITY, was the proportion active of the total 
number out. 
The fitting involved above should increase the information con¬ 
tent in any given variable. How important is this for taxonomic 
discrimination? To help answer the question, single “hourly” (i e 
nonfitted) variables were also tested (Table 1), each being simply the 
value, for a particular hour. 
Table 1. (see following pages) 
Means of variables examined for taxonomic value, averaged over days (May 
27-29 except where noted) and replicate nests for each species (abbreviated by 
initial of genus and species), totalout and temperature based on arc sine transfor¬ 
mation of count; position based on raw count; activity based on log of proportion 
active. Smufoidality represented by log of F statistic, Acropha.se by clock hour 
(decimal form: e.g-., 15.8 = 3:48 PM; angular avg), and Level and Amplitude by 
number of ants (except for POsmoN, where Level and Amplitude represent distance 
into arena-see text); these first 4 variables under each type of assay are all derived 
by least-squares cosine-fitting (Halberg et al„ 1972). The next 6 variables under 
TOTAL OUT are: Shift of Acrophase (no. of h change in acrophase from May 27 to 
May 29); Rt.se (h at which count passed up through avg [Level] for the day)- Shift of 
Rise (no. of h change from May 27 to May 29); Above Average (no. of h above avg 
for the day. May 30-31, when observed all 24 h); Light-on Difference (between count 
immediately after lights on and 2d count several min later, May 28-30); Fluctuation 
(no. of runs, where “run” = series of hourly values each having saSe sign of change 
from preceding value). Corresponding to latter is Fluctuation under position 
Finally, under each type are listed the hourly values, unprocessed except for initial 
transformation and averaging (activity 0700 omitted because could not observe all 
replicates simultaneously at the moment lights came on). F based on 5,20 degrees of 
freedom (slightly less for some variables with missing observations)- * = p< 05 ** 
= <. 01 , *** = <. 001 . 
