NOTES ON COMPARATIVE REGENERATION 

 IN ELODEA AND CERATOPHYLLUM 



By N. M. Grikr, Ph. D. 



WHILE quite unrelated from other standpoints, Elodea 

 and Ceratop/iylhiiii have certain characteristics in com- 

 mon, namely a habitat in slow streams and ponds and some- 

 what convergent, if superficial, anatomical structure, as 

 represented by the arrangement of their leaves in whorls. 

 The latter may represent a response to the particular condi- 

 tions under which they live, and from such a standpoint, a 

 study of their comparative regenerative power may be of 

 interest. 



Certain observations on these two plants may be added as 

 having relation to the data hereafter presented. Branching of 

 the stem in Ccratophyllum is much closer than in lllodca, the 

 great majority of the branches being but one node apart. In 

 a few specimens, this distance may be greater, sometimes as 

 much as 13 segments. During growth, the terminal bud of 

 Cerat()/'>/iylluiii appears to fre(|uentl\' (H\idc, producing imti- 

 mately a forked terminus to that portion of the plant. This 

 seems to be rarelv the case in Blodca, which however produces 

 what the writer lias never observed in a(|uariuni specimens of 

 CeratophyUiiui — adventitious or water roots. From the 

 aspect of com])ensal(»r\- growth, the broader and closely dis- 

 tributed leaves of lllodca find tlieir e(|uivalent in tlie compound, 

 divergent and threadlike leaf structures of Ccratophylluiii. 



Conclusions from a study of regeneration in the water 

 weed, Elodea canadensis, Mich.x. as published in The 

 American Botanist are largely derived from the table to 



