IV PREFACE. 



actively cultivated during the last few years, and are not so extensive 

 in their scope as those of Generation and Development. A larger 

 space has, therefore, been devoted to the latter, than to the former sub- 

 jects. To the Physiology of the Mind, for reasons which it is unnecessary 

 to explain, no additions have been made. 



It remains only to state that the portion of this work, comprehending 

 the following subjects : " The Unimpregnated Ovum," " the Semen," 

 " the Discharge of Ova from the Ovaries," " the Nature and Purport 

 of the Corpus Luteum," " Menstruation," and " the Changes which take 

 place in the Impregnated Ovum, down to the completion of the Cleaving- 

 process," has been written by myself, the greater part of it during the 

 winter of the years 1845-6; that the remainder has been written by 

 Dr. Kirkes, and that the whole has been prepared for the press by Dr. 

 Kirkes and myself conjointly. 



WILLIAM BALY. 



28, Spring Gardens, 

 27th March, 1848. 



