178 



AGGREGATION, COMPETITION AND CYCLES 



ANIMAL CYCLES IN THE FAR NORTH 



ANNUAL TAKE OF FURS BY THE HUDSON'S BAY CO., 1821- 1910 



Fig. 37. — Sunspot cycles are shown in connection with Hudson Bay fur receipts. 

 Small capital M indicates minimum and large capital M indicates maximum. 



1923 



1924 



Fig. 38. — Showing variation in the number and weight of the larvae of Chiro- 

 nomus from month to month, April, 1923, through April, 1925, in Flatten Lake 

 (Ploner Becken). The short dashes are for the numbers of C. hathophilus larvae; 

 the long dashes for the numbers of C. qylumoms larvae; and the dot-dash line 

 is for the total weight of larvae of both species. This is the average for the 

 whole lake for the second year and all but the zone to 4 meters for the first. 



(After Lundbeck, 1926.) 



