Sometimes adults who are not used to youngsters, but find themselves addressing a group of them, assume a ghastly sprightliness, a desperately arch tone. That seems to be the case with Mr. Aiken in his first book of poetry for children. The rhymes jingle and the attempts at humor jangle. Each of the 16 poems is devoted to an animal or bird. Consider this from ""The Fallow Deer"": ""You ask me/why they call him fallow/it is because/he's/kind of yallow/when he is young/he has a dapple/and/o/my/how/he/loves/an/apple."" (Please note the strokes. These indicate the length of line.) Many of the poems are laid out in this skinny fashion and the eye swims in empty white space. On the other hand, the illustrations are distinctive, fill each facing page. The artist has employed a different technique for each animal and his use of color is striking. One of the functions of poetry is supposed to be pictures in words, but here the pictures are all in the illustrations.