OF ARTS AND SCIENCES. 51 



mutual relationship, thus presenting a marked analogy to those Asco- 

 mycetous fungi in which the fruit arises as the result of a purely 

 vegetative process of hyphal growth. 



In conclusion, I must express my thanks to Dr. "W. G. Farlow 

 who, during the course of my investigations, very kindly allowed me 

 the free use of his herbarium and library. 



EXPLANATION OF THE PLATES* 

 Plate I. 



Figs. 1-3. Stida anthraspis, Ach. Asci and paraphyses after treatment with 

 iodine. X 500. 



Figs. 4-G. Sticta amplissima, (^co^.) M-inss. Asci and paraphyses after treat- 

 ment with iodine. X 500. 



Figs. 7, 8. Peltigera polydadijla, (Neck.) Hoffm. Asci and paraphyses after 

 treatment with iodine. X 500. 



Figs. 9-11. Nephroma tomentosum, (Hoffm.) Krb. Asci and paraphyses after 

 treatment with iodine. X 500. 



Plate II. 



Pannaria molybdea, (Pers.) Tuck. 



Fig. 12. Cross-section of margin of thallus with immature apothecium. X 110. 



The outline is drawn with the camera, the detail being drawn free-hand. 

 Fig. 13. Portion of an older hymenium near the margin, with asci, paraphyses, 



and subhymenial tissue. Free-hand drawing, partially diagrammatic. 

 Figs. 14-16. Asci and paraphyses. X 500. 

 Fig. 17. Isolated gonidia. X 500. 



Plate UI. 



Pannaria rubiginosa, (Thunb.) Delis. 



Fig. 18. Portion oT immature apothecium. Free-hand drawing, partially dia- 

 grammatic. 



Fig. 19. Isolated colonies of gonidia. X 500. 



Figs. 20, 21. Asci and paraphyses, after treatment with a very dilute solution 

 of iodine and potassic iodide. X 500. 



Fig. 22. Cross-section of thallus. Tlie outline drawn with the camera, the 

 detail completed free-hand. X 140. 



* The drawings in all cases, unless otherwise stated, were made with the aid 

 of the camera lucida. The paraphyses are colored darker by the iodine than 

 the cells from which they arise. 



