Problems of Fertilization.

Since the two primary impulses of all life are self preservation and race preservation, man has always been interested in the method of reproducing his kind and in the various physiologic and pathologic factors that are involved. After an enlightening history of early studies on this subject, Dr. Lillie presents briefly the morphology of fertilization, the physiology of the sperm cell and all the processes of fertilization, the problem of specificity in fertilization and the problem of activation. The theory of Dr. Lillie has been that the spermatozoon undergoes some activation necessary for its part in the internal events of fertilization: in other words, that the spermatozoon itself needs to be fertilized and that this takes place on its passage through the cortex of the ovum. In presenting other theories of activation, the author points out the plausibility of this particular view. To those already well grounded in elementary embryology,