88 THE NA TURE-STUD Y RE VIE W [ 4!J — mab., 1908 



their own ways of drawing. This was the close of the lesson. The 

 teacher instructed them to cover their glasses with pieces of 

 mosquito-netting, held in place by rubber bands, and told them 

 that the' glasses would not be touched until the next lesson which 

 was to occur two or three days later. The time of the lesson was 

 approximately thirty minutes. 



At the beginning of the second lesson it was to be noticed that 

 pupae had developed from some of the mosquitoes under the 

 netting, and it was evident to the pupils that these must have 

 developed from the larva? which had been studied and left in the 

 glasses at the end of the first lesson. 



The teacher began the lesson by asking, "Have your larvas 

 changed since the last lesson ?" The first answer was typical of a 

 number: "We have in the glasses some things which are black 

 with queer, hunched-up backs." The teacher said, "These are 

 called pupae. Look carefully and tell me what you see." In a 

 moment came the answer, "The pupae float up like a balloon, but 

 they have a mighty hard time getting down." Another pupil 

 said, "When they get down they paddle and paddle and when 

 they stop paddling they shoot up to the surface." The teacher 

 asked, ' ' Do they stick their tails out at the surface as did the larvae, ' ' 

 and in a moment several pupils replied, "No, they stick their 

 hunched backs out." The teacher said, "Look carefully at this 

 back." A pupil replied, "I see two horns." The other pupils 

 verified this observation. The teacher asked them what these 

 horns might be for and several pupils in chorus answered, "For 

 breathing." Other remarks showed that the pupils inferred this 

 because the tubes projecting out of the water in the larva stage 

 were used for breathing. 



The teacher instructed the pupils to watch for eating. There 

 were no results. The teacher asked, "Do the pupae of butterflies 

 eat?" A pupil replied, "No, for those pupae are quiet and do not 

 need to eat, but these pupae are moving and need food to keep 

 them going." Another pupil remarked, "Bears do not eat in 

 winter when they curl up andgo to sleep." The teacher explained 

 that an active pupae stage could exist without food because of its 

 short duration. 



Then the teacher poured some of the pupae out into watch 

 crvstals and used a handdens as in the first lesson. Vai"ious 

 pupils reported that they could not see a head. One of them 



