1912] Read: Suckling Period in the Guinea-Pig 347 
Per cent 
zl oy — Weaned at 21 days 
-~—~— Weaned at 10 days 
=I 
5 10 15 20 25 Days 
Fig. 1. Solid line shows the average growth of guinea-pigs weaned at 
twenty-one days, based on twenty-eight observations. The broken line 
shows the growth of W (2) weaned at ten days. The arrows on each line 
mark the termination of the suckling period. Data taken from table four, 
columns one and two. 
In a litter of three there were two animals which were the 
heaviest and lightest I have yet seen, weighing at birth respec- 
tively 94 and 57 grams. These two animals were selected for 
early weaning. 
The larger one (Ca) was weaned at the end of six days and 
nineteen hours (seven days). It lost 3.6 per cent of its weight 
by the end of the second day. But at the end of the third day 
it began to regain its weight, as is shown in column four, table 
IV. It required about twenty-seven days in which to double its 
weight. 
