weed] TREES IN WINTER 253 



tensely bitter taste of the bark. I see no objection to having the 

 pupils utilize the sense of taste in this connection, providing" the 

 teacher has been careful to warn them against tasting the poison 

 ivy and the poison sumac and has led them to recognize these 

 plants at sight. 



For young children this tasting of the twigs will be of great 

 value in exercising the special sense of taste, and perhaps to a 

 less degree it will have a similar value for older children. It 

 certainly will give excellent opportunities for careful discrimi- 

 nation and will greatly lengthen the list of objects for taste 

 images such as that given on page 143 of Professor Halleck's 

 " Education of the Central Nervous System," in his admirable 

 chapter on " Special Sensory Training." 



It is very generallv stated that the woolliness on the scales of 

 the buds of trees and shrubs is for the purpose of keeping the 

 miniature leaves and blossoms warm through the winter. Of 

 course it is easily realized that such a thin covering would prove 

 utterly inadequate in keeping out a freezing temperature from the 

 delicate buds. The botanists seem to be generally agreed that 

 such coverings are for the protection of the bud, but that this 

 protection is primarily brought about by preventing evaporation 

 from the tender tissues beneath the bud scales. It has been shown 

 that when the ground is frozen so that no watery sap can get 

 into vegetable tissues the injury from evaporation of the tissues 

 exposed to drying winds may be very severe. Consequently it 

 is found that plants generally protect their tender developing 

 parts in some way which will prevent undue loss of moisture 

 through the winter months. This seems an adequate explanation 

 of the woolly structure of many bud scales, of the wax-like cover- 

 ing of others, and of the varnish coating of buds like those of the 

 horse-chestnut. 



Teachers should be careful to select from the mass of conjec- 

 tures which pupils will make when asked to suggest explanations 

 for facts in nature only those which are founded upon actual 

 conditions that may so far as possible be seen by the pupil. An 

 analogy may easily be drawn in this case between the wilting of 

 a branch cut off and thus separated from its normal supply of 

 moisture and the conditions in the frozen ground. Should some 

 bright pupil ask how it is with the leaves of the hepatica and the 

 trailing arbutus which are exposed through the winter months, 



