BIOLOGY AND HUMAN WELFARE 3 



and he decides to try his luck elsewhere, a decision hastened 

 by the numerous mosquitoes in this shaded spot. Passing a 

 sandy shore he sees a large bass move hastily away. Here 

 he at once seats himself on a stone and throws his line out 

 near some lily pads. It is sunny and hot and still and the 

 horse flies and the sand flies pester him; but if he can only 

 catch that bass his mother will perhaps forgive him for the 

 milk. Three of those small flsh called pumpkin seeds and 

 two small yellow perch eventually reward his efforts, but in 

 catching them he loses both his hooks. 



He now remembers that he had promised dad to spend the 

 day searching for caterpillars on the tomato plants, for which 

 the reward was to have been two cents a dozen; he also re- 

 members other things, for instance, dinner time is twelve and it 

 is now three. Slowly he rises, to see the bass dart off again, 

 and gingerly collects his fish now encompassed with flies and a 

 few hornets. 



His welcome home is quite as he expected. His mother 

 did not mind the milk, but when he left the house he wedged 

 the screen door open in order to get out his precious pole, and 

 the house is full of flies. However, mother soon forgives him, 

 lunch revives him, and the tomato patch yields many worms 

 before dad returns. 



Now what are the biological contacts of Willie's day a-fish- 

 ing? 



Willie's woollen trousers were made from the wool of sheep 

 from England. For centuries the ancestors of these sheep had 

 been carefully selected in order to produce a strain that would 

 yield the longest and most abundant wool instead of long hair 

 mixed with short wool, the natural covering of sheep. 



The breeding of animals is by no means a simple matter. 

 In the old days long continued more or less haphazard efforts 

 were attended eventually by more or less success. Recently, 

 however, the subject has been studied in great detail and 

 certain laws determined by the application of which desired 

 results may be obtained, or at least approximated, with a 



