PREFACE 
The following memoir combines in one publication two separate papers 
which deal with the processes involved in the imbedding of the human 
ovum. They have been associated because of the complementary nature 
of the evidence they afford regarding the histological characters and the 
activities of the trophoblast. Each breaks new ground, in respect that 
while the first paper embodies a description of the earliest phase of the 
human ovum yet recorded, the second deals with the earliest case of 
ovarian pregnancy hitherto reported. 
The fact that the extremely early ovum described in the first paper 
is a unique specimen presenting features which liave not up to the present 
been observed, necessitated profuse illustration both by coloured plates 
and photographic figures. This has rendered the production a costly 
one, and we desire to express our obligations to the Carnegie Trust of the 
Scottish Universities for giving us a grant towards the expenses of 
publication. 
University of Glasgow, 
July 15 th, 1908. 
