atjthor's abstract of this paper issued 

 by the bibliographic service, february 2 



AMAROUCIUM PELLUCIDUM (LEIDY) FORM 

 CONSTELLATUM (VERRILL) 



I. THE ACTIVITIES AND REACTIONS OF THE TADPOLE LARVA 



CASWELL GRAVE 



Washington University, St. Louis, Missouri 



FOUR FIGURES 



A study of the organization, activities, and metamorphosis of 

 the free-swimming larva of Amaroucium pellucidum constellatum 

 was begun during the summer of 1912 at the Marine Biological 

 Laboratory at Woods Hole, Massachusetts, and has been con- 

 tinued as opportunities have permitted. It has also included 

 work on the structure and asexual reproduction of the primary 

 ascidiozooid and the formation of colonies and the differentia- 

 tion of germ cells by the secondary ascidiozooids. 



The "observations made on the activities and reactions of the 

 tadpole during its free-swimming period are recorded in this 

 paper. The histological structure of the organs involved in 

 larval activities will be described and figured in a paper now 

 being prepared for publication on the organization of the Ama- 

 roucium tadpole. 



LOCOMOTION 



Since the discovery of the chordate affinities of ascidians by 

 Kowalevsky, in 1866, a closer similarity in the behavior, as well 

 as the fundamental structure, of the ascidian tadpole with 

 chordate animals has been taken for granted than is apparently 

 warranted. In the numerous papers which have been published 

 on the development and metamorphosis of ascidians very few 

 observations on the behavior of the free-swimming larva have 

 been recorded. MacBride,^ in his Text Book of Embryology, 

 page 619, states that the tadpole larva propels itself like a fish 



239 



