GREGG] NATURE STUDY AXD HYGIEXE 271 



for the pupils, but because of what they may be able to accom- 

 plish in supplementing the efforts of the home. An additional 

 justification for the study of teeth in the fourth or fifth grade 

 lies in the fact that chidren in these grades are in the years of 

 second dentition and this furnishes adequate motivation. 



The studies here reported are quite as they were given to 

 three successive classes of children in the training school of the 

 Peru (Xebr.) State Normal School. At the end of the studies 

 not a few of the children, having retired at night without first 

 brushing the teeth, would rise on recalling this neglect and go 

 through the brushing operation. This happened a number of 

 times in the case of a little girl in the writer's own home. 



A. Preliminary Studies. 



It would be quite advantageous, not only for the study of 

 teeth, but also for other hygienic studies, if some inquiry could 

 be made, in the nature study way. of certain conditions and 

 results of germ activity. A culture medium such as is described 

 on page 274. \'ol. \TI (1911) of The X.xture-Study Review. 

 could well be employed in a gross study of germs. Touching 

 one of these gelatin perparations with a bit of decaying fruit and 

 another with scrapings from the teeth will yield readily observ- 

 able colonies of germs in two or three days, particularly if they 

 (especially the latter) be kept at 90 to 9.5 degrees F. The suitable 

 germ studies will bring out the fact that germs thrive where 

 there is food, and where it is warm, moist, and dark. 



B. The Nature-Study Approach. 

 (1). Number and Kinds of Teeth. 



(a). Instead of sending the pupils to the books to find out 

 in the purely bookish way the number of teeth at the various 

 stages of development, assign as a study to be reported on at 

 the next recitation hour the number of teeth each pupil mav find 

 in his own and his larger and smaller playmates' mouths. 



(b). With this same assignment there should go one requir- 

 ing the pupil to study, with the aid of a mirror ( pocket mirrors 

 such as are often given away for advertising purposes serve 

 admirably) his own teeth so as to be able to describe their appear- 

 ance and differences. 



(c). At the class hour the pupils report their discoveries. If 

 the teacher desires to give the technical names for the various 

 groups of teeth, the necessary motivation may be secured bv ask- 

 ing the pupils if they would like to be able to talk to the doctor. 



