OF ARTS AND SCIENCES. 57 



ed on its career, becomes further modified by differentiation, 

 specialization, elimination, adaptation, and so on. 



The polymorphism of the individual was next taken up and 

 it was shown how, as in entomology individuals are subject to 

 metamorphosis, as it is called, so in botany there are two or 

 more stages in the life history of plants. These .stages are usu- 

 a:lly called "alternation of generations," i. e., an alternation of 

 non-sexual with sexual generation, in which the products of 

 one process differ from those of the other. Then followed an ac- 

 count of the discovery of the process of reproduction in ferns, 

 and credit was given to Nageli, who, in 1844, found the anther- 

 idia, and Suminski, who, in 1848, found the archegonia. The 

 terms gametophyte and sporophyte were explained, and it was 

 stated how closely the gametophyte in the Pteridophytes resem- 

 bles the liverwort in the Bryophytes. 



By means of a diagram on the blackboard, the derivation of 

 the Pteridophytes was indicated and the probable derivation and 

 relations of the several orders in the sub-kingdom traced. The 

 Kquisetacese, Lycopodiacese and Ophioglossacese were described 

 as very ancient forms, plants allied to the lyycopodiaceae being 

 the probable source of the Gymnosperms, and plants allied to 

 the Ophioglossacese being the probable source of the Angio- 

 sperms, while the Equisetacese and their allies failed to develop 

 into higher forms. The Osmundacese were described as a con- 

 necting link between the Ophioglossaceas and the more modern 

 forms, the sporangia being derived parti}- from epidermal cells 

 and partly from the interior tissue of the leaf, instead of being 

 derived wholly from the interior tissue, as in the Ophioglossa- 

 cese, or wholly from epidermal cells, as in the Polypodiacese. 



Adjourned to April 10. 



Tuesday evening, April 10. Regular meeting ; the President 

 in the chair. After routine business the evening was devoted to 

 the study of Buds, Anients and Catkins, specimens being shown 

 from various species of trees and shrubs. 



Adjourned to April 24. 



Tuesday evening, April 24. Regular meeting ; the President 



