STUDIES ON THE FERTILIZATION OF PLANTS. 211 



on the living limbs, but the dead branches broken by late summer winds 

 give the proof, if any is needed. 



Closer observation of the black oak reveals the little miniature acorns, 

 on the previous year's growth, in the axils of the leaves. It would re- 

 quire little reflection to see that these are the acorns to ripen in the fall. 



In similar positions on the fresh young shoots of this spring's growth, 

 in the axils of young leaves, may be found corresponding structures one 

 year younger. The fleshy growth with the three reflected lips is the 

 female flower. But 'what a flower!' I exclaimed, when I first saw it. 

 It is devoid of the showy envelope which we associate with this word. A 

 perfect flower is one that has both pistils and stamens; that of the oak 

 has a pistil only, or anthers only. It is therefore an imperfect flower. A 

 flower with both pistils and stamens and both whorls of the floral en- 

 velope — the outer one, the calyx and the inner, the corolla — is called 

 a complete flower. Such is the apple blossom. 



The sticky surfaces of the three lips are the stigmatic surfaces and 

 the part bearing them — the stigma. The swollen attached end is the 

 ovaiy. The stem connecting the stigma with the ovary, in this case 

 quite short, is the style. 



Sections of the ovary show that the exterior part is a covering for 

 the seed like ovule. By proper methods we could go further and demon- 

 strate the germ cell itself which is in reality the center of life and the cell 

 from which the future oak is to spring. 



Near the attached end of the ovule is a small opening into the ovule 

 called the micropyle. By the provisions of nature no plant germ cell 

 can divide and grow into an embryo without the introduction through 

 this micropyle of the growing pollen tube. This pollen tube can grow 

 only when a ripened grain of pollen produced on the anther of the same 

 or another flower, falls upon the stigmatic surface of the pistil when it 

 is in a receptive state. The conditions under which fertilization takes 

 place, for this is the name given to the process just described, form an 

 interesting chapter m plant morphology and plant physiology. 



It is my purpose to call your attention to some of the wonderful 

 adaptations in plants and animals which are evidently solely for the pur- 

 pose of transferring the ripened pollen to the receptive stigmatic surface. 



Let us take up the case of the oak. As was stated, the fruit bearing 

 oak is imperfect, and consists of a pistil only. We must look for another 

 flower,, therefore, which shall contain the stamens,. We call the 

 pistil just examined the pistillate flower,. Let us look for the stamens 

 or the staminate flower. In some cases we must look on another plant. 

 When pistillate and staminate flowers are found on separate plants we 

 have a dioecious plant. In the black oak we find the staminate fiowers 

 on the preceding year's growth in the axils of leaves. Such fiowers are 

 called monoecious. 



If you examine the long catkins or aments it will be found that the 

 stamens are borne upon a long stalk. When viewed through a lens a 

 beautiful structure is disclosed. Each stem bears numerous flowers and 

 each flower contains four stamens. 



The drawing (Fig. 6) shows the anther on the pollen bearing part. 



