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phores (names repulsive enough to any student), the hidden an- 

 theridia, and the small sphorophytes with their delicate vestments 

 difficult to demonstrate, make MarcJiantia a formidable object to 

 the beginner. His mind becomes so crowded with detail that he 

 is apt to overlook the fundamental relations. 



Contrasted with Majxhantia let us take such a type as Palla- 

 vicinia. In Fig. i is shown in the same section a longitudinal 



Fig. I. Cross-section of female gametophyte of Pallavicinia Lyellii, showing 

 involucre, perianth, archegonium, and young sporophyte. 



view of the young sporophyte and transverse view of the game- 

 tophyte. All parts are shown and their relations are absolutely 

 clear. Take four such sections at different ages, beginning with 

 the mature archegonium, and the whole subject of alternation is 

 presented. The gametophyte is so simple that it can be under- 

 stood at once and the sphorophyte is so large and conspicuous 

 as to prepare the student for the next step. The male plant is 

 equally simple, and the antheridia can be seen with the naked 

 eye without any dissection. A cross-section of the male plant 

 through an antheridium is shown in Fig. 2. The only deficiency 

 of Pallavicinia is the absence of gemmae, but for the study of 



