168 THE DISCOVERY OF THE CHILD to us small herbs which we had not cultivated and which we did not know to have scent; but when the children insisted and we smelt them, we discovered that they really possessed a delicate perfume. The ground thus cultivated, in which uniformity of colour and only slight differences in shape combine to isolate, up to a certain point, the olfactory sensations, is a place of 'research* and therefore of exercise for the olfactory sense. When the attention is directed methodically into activity through various sensorial stimuli, even smell is more intelligently exercised and becomes an organ for exploring the surroundings. But that smell acts naturally in conjunction with taste in the act of feeding was more clearly shown to us even in the smallest children through their ability to choose or to reject foods. This part of education is mixed up with nutritional life, but is so deli- cate that it deserves special treatment. Remembering that taste identifies only the four fundamental tastes, one understands how it is that the most natural place to exercise the olfactory sense is that of the meal. Getting children to distinguish sensations due solely to taste, to know the four fundamental tastes, excites undoubted interest. Whilst sweet and saline are both pleasing tastes, even bitter is tried as an experiment, and acid, especially in various fruits, is distinguished in its different degrees. Once interest has been roused in tastes and the very distinct limitation of them, the world of odours is distinguished more clearly in the vast variety of those mixed sensations of smell and taste which is met with in nutrition-—as in milk, fresh and dry bread, soup, fruit, etc. And the tactile sensations of the tongue, such as those of sticky, oily substances, are distinguished from those of taste and smell through an effort of the intelligence which is a real and proper exploration of oneself and of the environment. The method of touching the tongue with a specific solution— bitter, acid, sweet or salt—such as is used in estesiometry,1 was 1 Measurement of sensibility.