CONTENTS
[PREFACE]
[CHAPTER I]
[CHAPTER II]
[CHAPTER III]
[PREFACE]
The facts observed and recorded by others assisted me to advance so far on the trodden path that I made an effort to snatch a secret from Nature.
What I succeeded in obtaining, though small, induced me to set forth in the following pages the perhaps not unimportant results.
The labor was long, and engaged my attention for years. And yet, amidst my continuous labors in the province of Embryology, it remained all the time a matter of secondary importance, my principal attention being engaged by far more extensive studies.
My desire is to stimulate others to wider observation. May the facts which I here discuss prove of utility, and encourage further studies in this direction with the assistance of modern science.