180 PROCEEDINGS OF THE AMERICAN ACADEMY 



impressions of the vessels of vegetables, and were not caused 

 by the action of sliding in the veins ; he thought that no acci- 

 dental sliding could produce such uniform marks on numerous 

 specimens from various mines. 



Mr. Teschemacher also exhibited some rhizomorphas, found 

 in the old chambers of coal-mines. 



Professor Agassiz called the attention of the Academy to the 

 importance of a complete investigation of the anatomy, the 

 mode of life, and the embryology of the blind-fish of the 

 Mammoth Cave {Amhlyopsis spelcEus). He thought there was 

 an opportunity to settle, by actual experiment, the extent of 

 physical influences in causing organized beings to assume their 

 peculiar and distinctive characteristics in relation to the media 

 in which they live. He doubted not that important inferen- 

 ces could be derived from these investigations with reference 

 to the question, whether species have been created in the lo- 

 calities they inhabit and with special adaptation to the external 

 circumstances in which they were first introduced, or wheth- 

 er these circumstances were acting as modifying influences 

 upon fewer primitive types, which would thus be diversified 

 and produce the successive changes evinced in the geological 

 series. The experiments he would suggest are, first, an ac- 

 curate and complete anatomical investigation, sufliciently mi- 

 nute to enable the observer to perceive the slightest changes 

 which would occur ; secondly, observations upon individuals of 

 different ages brought to the light and kept for a long time, 

 even through a series of successive generations, in these new 

 circumstances ; thirdly, a complete series of comparative embry- 

 onic investigations with recently laid ova, traced simultaneous- 

 ly in the dark and under the influence of moderate and of in- 

 tense light, keeping especially in view the formation of the ner- 

 vous system, and particularly that of the eyes. If there is an eye 

 formed in the dark, ascertain when and how it disappears, as it 

 is entirely wanting in the full-grown individuals, and again no- 

 tice the diff'erences in this respect between specimens growing 

 under the influence of light. 



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