Now let us look at the structure of the ripe seeds themselves, and see how they are fitted to go out alone into the world prepared to make a new plant. Seeds are all very much alike in the important points of their structure, although they vary much in the shape, size, and colour of their parts. We already know what beans are like from our careful study of them at the beginning of our work (~see~ Chapter III.), and beans show us particularly well all the important parts of a true seed, so that we may take them as being typical of one large family of flowering plants. The maize embryo (~see~ p. 10) is typical of the rest of the flowering plants. ~In the ripe seeds~ of both of these groups (you should examine them again if you have forgotten any of the facts) we find that ~the important thing is the baby plant~, which is supplied with food and ~protected by two seed coats~, till it is time for it to grow out and form a new plant like its parent. [Illustration: Fig. 89. A, outside of Bean; (~h~) black scar showing where the bean was attached to the pod; (~r~) ridge made by young root; B, bean split open; (~n~) nurse leaves; (~p~) embryo; (~a~) scar where the embryo was separated from the nurse leaf on that side.] [Illustration: Fig. 90. A, outside of Maize, showing the embryo (~e~) on one side; B, sprouting, showing the root (~r~) and shoot (~s~); C, the same further grown.] CHAPTER XVII. THE TISSUES BUILDING UP THE PLANT BODY [Illustration: Fig. 91. Two cells from plant tissue. (~c~) Living contents; (~n~) cell nucleus; (~v~) spaces filled with sap; (~w~) wall of cell (much magnified).]