178 KANSAS UNIVERSITY SCIENCE BULLETIN. 



stains and fixatives were employed in preparing the material 

 for histological study, and camera drawings were made of 

 some of the specimens. 



At present only five sets of experiments were pursued, and 

 for these controls were kept. 



1. From a free-swimming larva the entire tail, with its noto- 

 chord, nerves, muscles and tunic, was removed. 



2. From young embryos the anlage of the tail was dissected. 

 The results from these two sets of experiments were that the 



organisms developed quite normally, but were smaller than the 

 normal control. 



3. Removed from a free-swimming larva the tail and also 

 the nervous system with its sense organs. 



4. Removed from young embryos the anlage of the tail and 

 the nervous system, staining them, as well as the control, after 

 four days with methylene blue. 



The results from these two sets of experiments were that 

 they developed much smaller than the control, many were 

 abnormal, and in four or five days the heart began to beat and 

 the siphons contracted when touched. The contractions were 

 slower and not as complete as in the control, and at this time 

 I can not state positively that the heart reverses its rhythm 

 spontaneously. 



5. Removed the nervous system and the heart anlage from 

 young embryos. In some only part of the nervous system had 

 been removed, as shown by the methylene-blue staining. The 

 resulting cell complex developed into an abnormal structure 

 devoid of heart and siphons, and with an incomplete digestive 

 system. In those that retained part of the nervous system and 

 pharyngeal cells, only one siphon developed. In others, in 

 which the nervous system and part of the pharyngeal cells 

 were removed but not the heart anlage, the structure regen- 

 erated its tunic, which contained, after four days, an abnor- 

 mally formed digestive tract with a beating heart and one 

 siphon. 



We may conclude : that the cells which give rise to the heart, 

 siphon and digestive tract continue to develop after the nervous 

 system has been removed ; the cells are independent living 

 structures, capable of continuing their growth in a suitable 



