OF ARTS AND SCIENCES. 73 



instance, certain examples bore archegonia with embryonal outgrowth, 

 and others only direct bud-development, it is of course interesting to 

 know whether the young plantlets of the two kinds of origin exactly 

 resemble one another in their after development. For this purpose, a 

 number of specimens evidently belonging to the category of abnormal 

 growths were transplanted into a pot where their growth could be 

 watched. So far there is no difference between their growth and that 

 of plantlets developed from embryos. 



In conclusion, I would take this opportunity to thank Professor De 

 Bary of Strasburg for material and advice kindly afforded during the 

 course of the foregoing investigations. 



EXPLANATION OF THE FIGURES. 



Figs. 1, 6, 9, 12, 13. Different forms of prothalli of Pteris serrulata, 

 slightly magnified. In all, a represents the original scalariform duct ; 

 h the first leaf; ?-root; and s the stem-bud. lu 12, V, /, s', represent 

 the coi-responding ports of a second plantlet. In all, the position of the 

 root-hairs and archegonia are seen in the lower part of the prothallus. 



Fig. 2. A longitudinal section of fig. 1. 



Fig. 3. A-^iew of a terminal growing cell of the same seen from above. 



Fig. 4. Section parallel with x, fig. 3, and more highly magnified. 



Fig. 5. A portion of fig. 1 seen from above ; a original scalariform duct ; 

 X signifies the same cells as in 2 and 4. 



Fig. 7. Longitudinal section of fig. 6, in which a represents the 

 upward-growing portion. Several antheridia are seen at one end. 



Fig. 8. Portion of a young prothallus, showing the growth in the con- 

 cavity and scalariform ducts in two groups. 



Fig. 10. Magnified view of fig. 9, showing the origins of two leaves and 

 the ducts lying behind in the prothallus. 



Fig. 11. Longitudinal section through the place of origin of a young 

 plantlet produced by dii-ect budding : b leaf, r root, s stem-bud, ;;,/>, 

 prothallus. 



Fig. 14. A corresponding section of a normally fertilized prothallus 

 and plantlet, copied from Sachs's Lehrbuch der Botanik : ^j,p, prothallus, 

 /foot, fZ,(Z, vascular bundle, b leaf, r root. 



Correction. — For Pteris serrulata, in the title and elsewhere, read Pteris 

 Cretica. The subsequent development of the plantlets has proved the latter 

 to be the species to which the protlialli belonged. — W. G. F. 



VOL. I. 



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