A STUDY OF PEDAL LACERATION IN ACTINIANS. 



LEWIS R. GARY. 



Since the appearance of Andres's ('82) classical paper "In- 

 torno alia Scissiparita della Attinae," the only accounts of the 

 process of pedal laceration have been very casual, or have been 

 given only for the sake of comparison with the phenomena of 

 induced regeneration. Carlgren ('04), ('09), who alone has 

 studied this form of reproduction in the genus Aiptasia, makes 

 mention only of the sequence of the appearance of the mesenteries 

 and tentacles, but gives no general account of the process, nor 

 does he mention any of the histological features. 



Since the last-mentioned phase of the subject is of considerable 

 interest as a comparison with the development of normal em- 

 bryos, it has seemed advisable to publish the following account 

 to supplement the previous contributions to the knowledge of 

 this type of reproduction which is so common among the 

 actinozoa. 



The observations herein recorded are based upon the study of 

 four species of actinians: Aiptasia pallida Agg., A. tageies D. 

 & M., A. annulata Andres and Cylista leucolena Agg. 1 Of these 

 species A. pallida and Cylista were obtained in abundance at 

 Beaufort, N. C., 2 during the summer of 1903 and 1904, where 

 they were studied both in their natural environment and in 

 aquaria in the laboratory. 



Specimens of the first-mentioned species were transferred to 

 Baltimore and kept during two years in aquaria in the zoological 

 laboratory of the Johns Hopkins University. By means of the 

 diatom method described by Dr. Caswell Grave for rearing 

 echinoderm larvae, the actinians were kept in good condition 



1 Professor McMurrich informs me that he has conclusive evidence that the 

 form described by Verrill from Beaufort, N. C., as C. leucolena is not the C. leucolena, 

 of A. Agassiz, but in the absence of any published statement to that effect Verrill's 

 terminology will be used. 



- 1 am indebted to the officials of the U. S. Bureau of Fisheries for the use of a 

 table, and equipment at their Beaufort, N. C., laboratory during the two seasons 

 above mentioned. 



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