THE KANSAS UNIVERSITY 

 SCIENCE BULLETIN. 



Vol. IX, No. 14.] SEPTEMBER, 1915. M£^K534 



The Development of a Tunicate 

 Without Nerves. 



IDA H. HYDE. 



From the Physiological Laboratory of the University of Kansas and the Woods Hole 



Biological Station. 



A PRELIMINARY report is here presented of experimental 

 work that deals with the differentiation of cardiac and 

 other tissue independent of nervous control. 



The organism employed was Ammaroecia, one of the Tuni- 

 cates found in Woods Hole. It is viviparous, bearing the 

 different stages of embryos in a definite sequence in the ova 

 sack. When the notochord and motile tail are developed the 

 larva swims out. It is active for about one hour, then attaches 

 itself to the dish by means of its adhesive papillae. In three 

 days the heart begins to beat, and in four days the tail is ab- 

 sorbed and the organism is quite well developed. The nervous 

 system, consisting of a vesicle formed of nerve cells and fibers, 

 contains two pigmented sense organs. It functions before the 

 pharynx, digestive system, and heart do. 



In embryos the anlage of the tail, nervous system, and di- 

 gestive tract can be recognized by the different-colored cells 

 and their position. 



For experimental purposes the embryos of different ages 

 were easily dissected from the ova sack with fine steel points 

 or hard glass fibers. Methylene blue and many other nerve 



Received for publication January 5, 1915. 



(177) 



