WHITE SUCKER 
171 
are the most widely spaced. However, equally wide spacing may occur in those of 
the middle part of the annual zone, which form during the summer. As a rule they 
show a progressive crowding from spring to late fall, when they probably cease to 
form. (Fig. 55.) 
Scale growth in the white sucker appears to be nearly at a standstill from 
November to late February. The evidence supporting this conclusion consists in 
finding that the number of circuli in the current annulus appears to be the same 
throughout this season, the full year’s quota being present in the fall. Again one 
frequently finds scars on the scales — that is, eroded edges — which apparently have 
thickened during the winter while growth was at a standstill. 
crowding of the circuli. Others have believed F,G - 54 '- Scctor of *** ^eighth or ninth year, speci- 
. men 375 millimeters 
that temperature regulated the spacing phe- 
nomenon. The sucker feeds well in November and February and probably all win- 
ter, though I have not observed it. The wide circuli observed for all specimens 
taken in early spring, even before the ice is out of the streams, can not be assigned 
to temperature as stimulating growth. 
The sucker spawns in April and May, and the gonads of the male are ripe as 
early as February. It may be that the ripening of the germ cells interferes with the 
nutrition of the other tissues of the body, and that this condition is responsible for 
the irregularity in the form of the circuli of early spring. Coupled with this is the 
