4 THE BOOK OF NATURE STUDY 



that are recorded. It does not very much matter what the leading 

 idea in the teacher's mind is that must depend on the individual 

 teacher but it is important that the lessons should succeed each 

 other in the order which best develops the conception that it is 

 desired to impart of Nature and her ways. 



STRUCTURE OF SEEDS. The study of Plant Life may be begun 

 with that of seedlings, and in order to understand the germination 

 of a seed, it is necessary first to know its structure. If the seeds 

 of various typical plants are examined, it will be found that the 

 essential part of all seeds is the embryo of the young plant. Now 

 it is obvious that the young plant must have something within 

 the seed to feed upon until it is able to obtain food-material for 

 itself from its surroundings, the air and the soil. This food- 

 material is sometimes contained within the embryo, sometimes 

 outside it. It is therefore necessary to examine several seeds, 

 and the following will be found representative types : i. Bean, 

 pea, mustard and cress, cucumber, all of which have food-material 

 contained in the embryo ; 2. Buckwheat, maize, wheat, barley, 

 which have food-material outside the embryo. 



To begin with the structure of the bean or pea. The mode in 

 which the seeds are attached in the pod is shown in the folded 

 diagram, inside the cover of Vol. IV. It will be noticed that the 

 pod, or seed-vessel, splits into two pieces, an experience familiar 

 to every one who has shelled peas. The seeds come off alternately 

 in the two pieces, but are all attached to the same edge of the seed- 

 vessel, each by a little stalk. It was by means of this stalk that 

 the bean plant was able to feed the seeds when they were 

 developing. The dry seeds of the broad bean are brown, convex 

 on one side, and more or less straight on the other. The 

 brown structure is the seed-coat ; on one side is a black scar 

 showing the position of the stalk, attaching the seed to the pod. 

 In seeds which have been soaked for twenty-four hours, the 

 seed-coat, which was at first wrinkled, becomes stretched, owing 

 to the water that has been absorbed. A triangular structure is 

 seen through the testa, the apex of the triangle pointing towards 

 the scar. This is the radicle, or first root. If a seed which has 

 been soaked is dried on the surface and then squeezed, water will 



