334 
Observations on Termites 
(4) Seasonal Variation. 
Material obtained from the same nest at different months exhibited variation 
in the means and standard deviations. In the first part of Table I. are given the 
records of seven nests from which material had been collected at different seasons, 
generally Nov., Jan., Mar., May and August. A comparison of the figures will 
show that as a rule the mean was lowest and the standard deviation greatest 
when the material was taken in November, while generally the mean was highest 
and the standard deviation smallest in the month of March. 
In the following table (Table II.) are given the arithmetic means of the means, 
standard deviations and the coefficients of variation of samples (varying from 72 to 
200 in number) of small soldiers and large workers taken from five nests " 668," 
" 670," " 672," " 674," " 67.5 " (see Table I.) in the months mentioned above. 
TABLE II. 
Termes Natalensis. 
Month of 
Colleotiug 
Means of the Five Nests 
Small Soldiers 
Large Workers 
Mean 
Standard 
Deviation 
Coefficient 
of 
Variation 
Mean 
Standard 
Deviation 
Coefficient 
of 
Variation 
November ... 
241 -2* 
9-00* 
3-75 
230-5* 
6-99* 
3-03 
January 
248-1 
7-38 
2-99 
234-5 
6-03 
2-59 
March 
2.51 -8 
6-56 
2-62 
241-6 
4-84 
2-01 
May 
245-2 
7 -.30 
3-00 
241-5 
6-12 
2-54 
August 
233-9 
8-06 
3-45 
230-7 
5-96 
2-58 
* Unit = -01 mm. 
This seasonal variation probably arises from two causes at least; (1) the 
elimination of the physically unfit, (2) post " adult " growth. With reference 
to the first cause it may be noticed that it is very probable that more individuals 
arrive at maturity from August to November, that is during the first rains, than 
at other seasons, and therefore the stunted adults will be more abundant during 
this period, with the result that the mean would be lowered and the standard 
deviation would be raised. By the time that March arrives the small and weakly 
individuals of the nest are likely to have died, and consequently the mean will 
be raised and the standard deviation will be diminished. The second, and 
perhaps more potent influence, is that the so-called "adults" appear to grow 
to a certain extent even after their exoskeleton has become hard and yellow. 
In the following table (Table III.) the frequencies for six nests are given for small 
soldiers and large workers mostly collected in November and March. 
