1912] Read: Suckling Period in the Guinea-Pig 349 
double the weight was eighteen days. Inspection of the growth 
curve in figure 3 shows that it follows the average curve very 
closely. 
Another animal (Be) which was born in the same litter with 
(Bb) was weaned at the end of the fourth day. The first day 
it lost 8 grams but at once began to gain, and on the third day 
after weaning its weight was the same as when taken from the 
mother. Its weights are given in the sixth column of table IV. 
Twenty-seven days after birth its weight had been doubled. 
Per cent 
1 — Weaned at 21 days 
ee Weaned at 6 days 
—— — Weaned at 4 days 
1 
5 10 15 20 25 Days 
Fig. 3. 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 Bb (4) weaned at six days. The dotted line marks 
the growth curve of Ba (gf) weaned at four days. The arrows on the three 
lines mark the termination of the suckling period. Data taken from 
table 4, columns one, five and six. 
