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Notes on the Rearing of Echinoid Larvae. 



By 



E. W. MacBride, M.A., D.Sc, 

 Professor of Zoology in McGill University, Montreal. 



The problem of successfully rearing the larvas of Echinoidea until they 

 had completed their metamorphosis, has been solved by several 

 naturalists. Agassiz* was able, for three weeks, to keep plutei alive 

 which he had fished from the sea, at the end of which time they sank 

 to the bottom and became young echini. Buryf was able also to rear 

 a few of the plutei of one of the Neapolitan species through the whole 

 of their larval life, and finally TheelJ has published an account of how 

 he obtained all stages in the development of Echinocyamus pusillus 

 from the result of artificial fertilisation. 



During the months of May and June in both 1898 and 1899, I was 

 occupied with a similar, though not identical problem. I wished to 

 obtain sufficient material of all the stages of development of Echinus 

 esculentus to enable me to make an exhaustive investigation of the 

 formation of all the organs of the adult Echinus. For this purpose it 

 was not sufficient to be able to rear one or two specimens through the 

 metamorphosis ; the question was to be able to obtain a considerable 

 number of late and metamorphosing stages. This end was finally 

 attained in July, 1899, twenty-four young echini and a large number 

 of plutei, with an advanced rudiment of the echinus within them, 

 were obtained. 



Keviewing the history of two seasons' experiments, it seems possible 

 to arrive at some idea of the conditions for the healthy life of these 

 larvai, and for the sake of future investigators these are outlined 

 here. 



The greatest number of experiments were made with Echinus 



* Revision of the Echini, L. AoASSiz. 

 t According to a statement made to the author in 1894. 



X "The Development of Echinocyamus pusillus," by H. Thi5el. Proceedings of the 

 lioyal Society of Sweden, Upsala, 1892. 



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