36 HAROLD SELLERS COLTi'V 



.1- .i whole \\as be^un in the /< >< 1< >^ical laboratory of the Univer- 

 sity of Pennsylvania. It \\a- continued at the Zoological Station 

 at Naples, at the Fisheries Laboratories at Woods Hole, and 

 I'., an fort , and the following part of it completed in the Zoological 

 Laboratory of the University of Pennsylvania. At this point 

 the writer wishes to express his great thanks to the Carnegie 

 Institution for the use of one of their tallies at the Naples Labora- 

 tory, to the authorities of the station for their many kindnesses 

 and hospitality, to the United States Commissioner of Fisheries 

 for the use of a table for two weeks at Woods Hole, and one for 

 t\\o weeks at Beaufort, and also to the directors of those stations, 

 1 )v. I-'. B. Sumner and Mr. H. D. Aller in particular. 



Although for this study most of the living material was pro- 

 cured in the salt-water tanks of the vivarium of the University 

 where Botryllus colonies have been established for many years, 

 \et the wealth of material preserved in Naples and Woods Hole 

 has often been called into requisition while living material of 

 other families of ascidians were studied at Beaufort. 



According to Bancroft ('03) there is but a single species of 

 Botryllns found in the north Atlantic Ocean and its extensions. 

 Many have been described, but they are found to be based on 

 color variations and habit of growth depending partly on the 

 age and partly on the physiological state of the colony. The 

 writer having worked at both Naples and at Woods Hole sup- 

 port > tin- view of Bancroft and considers that Botryllus schlosseri 

 (Pallas) Savigny, is the form represented on both sides of the 

 ocean. 



The material was fixed in Flemming's solution, in corrosi\e 

 sublimate, sublimate acetic, formol, etc. The best results were 

 procured with Flemming's solution. Sections were cut 6 ^ and 

 stained in Delaficld's ha'inatoxylene and eosin. However, most 

 of this study was made on t he living animals and sect ions were 

 Used only to check up the results. 



MoKi'in >\.( ii. V. 



The alimentary tract of Botryllns is of the typical ascidian 

 type and may be represented by the letter U of which one arm 

 will be the oesophagus and stomach while the other is represented 



