CHAPTER I 



INTRODUCTION 



Under the name Archegoniatae are included a large number 

 of plants which, while differing a good deal in many structural 

 details, still agree so closely in their essential points of 

 structure and development as to leave no room for doubting 

 their close relationship. Besides the Bryophytes and Pteri- 

 dophytes, which are ordinarily included under this head, the 

 Gymnospermae or Archespermse might very properly be also 

 embraced here, but we shall use the term in its more restricted 

 meaning. 



The term Archegoniatae has been applied to these plants 

 because the female reproductive organ or archegonium is 

 closely alike, both in origin and structure, in all of them . This ' 

 is a multicellular body, commonly flask-shaped, and either 

 entirely free or more or less coherent with the tissues of the 

 plant. In all cases there is an axial row of cells developed, of 

 which the lowest forms the egg. The others become more or 

 less completely disorganized and are discharged from the 

 archegonium at maturity. Among the Algas there is no form 

 at present known in which the female organ can be certainly 

 compared to the archegonium, although the oogonium of the 

 Characeae recalls it in some respects. 



The antheridium or male organ of the Archegoniats, while 

 it shows a good deal of similarity in all of them, still exhibits 

 much more variation than does the archegonium, and is more 

 easily comparable with the same organ in the Algae, especially 

 the Characeas. Like the archegonium it may be entirely free, 

 or even raised on a long pedicel ; or it may be completely sunk 

 in the tissue of the plant, or even be formed endogenously. It 

 usually consists of a single outer layer of cells containing 



