1918. | The Vitality of Silkworm Moths. 105 
recorded was 95 per cent. The maximum temperature in the 
experiment was 15°5°C and the minimum was 6°C. 
In his moisture experiments he showed that when there 
was a moderate increase in the relative humidity the death- 
rate was only 15 per cent but that it rose to 90 per cent in 
a saturated atmosphere, and that when there was a large 
increase in both temperature and moisture condition the 
mortality percentage rose to 95. 
rs experiments show how harmful a high average 
deviation of temperature can be to insect life. They also show 
that a large decrease in the temperature is also harmful, but 
not quite as much. 
In connection with this rise and fall of vitality in moths in 
relation to the seasons it is of interest to find that Birch, 
referring to statistics of soldiers’ children in India, which afford 
full information of the relative healthiness of each month, 
states: ‘‘ The most unhealthy months are, we see, July, August, 
beginning and fall from the end of the first-named period is 
marked by the figures with singular regularity. The increase 
of mortality and sickness is coincident with the advent of 
extreme heatanddamp.” The statistics he refers to show that 
the number of admissions into hospital in January was 440, 
while in August it was 1,360, and in September 1,024. The 
number of deaths for January was 41, for February 32, while 
in July it was 99, in August 155, and in September 
On the whole it seems very evident that the great heat 
and humidity to which most forms of life are subjected during 
the rainy season diminishes their vitality to a considerable 
extent. The dreaded month of May is somehow not so harm- 
ful as the Rains, which are looked forward to as a welcome 
break in the heat. 
ERRATA. 
On Plate II under Diagram III in the second group of figures repre- 
senting numbers of individuals, for 21.9.4 read 21.7. 4. 
On the same plate under Diagram IV in the same column, for 20. 7. 4 
read 21.7.4 
Sn ated 
