igis] HUTCHINSON— PELLI A EPIPHYLLA 143 



I am greatly indebted to Professor John M. Coulter for sug- 

 gestions and criticisms received, and to Dr. W. J. G. Land, under 

 whose direction the work was done. 



University of Chicago 



EXPLANATION OF PLATES I-IV 



All drawings were made with the aid of the Abbe camera lucida. Original 

 magnification of figs. 15, 40, and 50 was 500; of all other figures 1730. The 

 reduction in reproduction is one-third. 



Figs. 1-29. — The antheridium of Pellia epiphylla. 



Figs. 1-6. — Longitudinal sections of a young antheridium, such as is char- 

 acteristic of Jungermanniales. 



Figs. 7-9. — Cross-sections of the same. 



Figs. 10-12. — Cross-sections of antheridia of Pellia similar to those of 

 Spkaerocarpus or Marchantiales. 



Figs. 13, 14. — Sections through the stalk (fig. 13) and spermatogcnous 

 region (fig. 14), the latter illustrating two methods of growth. 



Fig. 15. — A double antheridium. 



Figs. 16-22. — Longitudinal sections of antheridia showing a development 

 similar to that of an archegonium. 



Figs. 23-25. — Similar to last, with the elimination of the cap cell. 



Figs. 26-29. — Cross-sections of the same. 



Figs. 30-40. — The archegonium. 



Figs. 30-38. — Longitudinal sections. 



Fig. 39. — Cross-section. 



Fig. 40. — Cross-section of archegonial pocket. 



Figs. 41-50. — Growth structures. 



Fig. 41. — A cuneate apical cell in young gametophyte which has just 

 escaped from the spore coat. 



Figs. 42, 43. — Sections of sporeling showing the segmentation of the 

 cuneate apical cell; fig. 42, vertical; fig. 43, horizontal section. 



Figs. 44, 45. — Transition forms of apical cells. 



Figs. 46-48. — Sections of the lenticular cylindric apical cell, also showing 

 the region surrounding; fig. 46, a transverse vertical section; fig. 47, a longi- 

 tudinal vertical section; fig. 48, a marginal longitudinal vertical section, 

 showing how the lateral segments produce the wing or lobe. 



Fig. 49. — A section through a region of apical growth. 



Fig. 50. — A young sporophyte inclosed by a somewhat massive calyptra 

 and the involucre; sterile archegonia on calyptra. 



