vorable positicns, and have their latent possibilities called 

 forth. 



Those which become attached at a point high up on 

 the right side of the inner vesicle in the posterior region 

 of the bud, v.'ill forin the pericardiim; others on the dorsal 

 side, at the anterior end, v/ill give rise to the dorsal tube, 

 and still others, v/hich lodge on the upper wall of the latter, 

 will help to construct the ganglion; sorrie adhere to the in- 

 ner surface of the ectoderm, lengthen out and become muscle- 

 fibres, some wander through the ectoderm, and on the external 

 surface are transformed into the cells of the cellulose test, 

 while others find a definite place in the posterior region 

 of the bud and develop into the sexual organs. 



This viev/ is opposed to the supposition of Seeliger 

 spoken of above, that in Clavelina the ganglion of the bud is 

 formed from free cells of the blood, v/hich had earlier com- 

 posed the larval ganglion and been liberated on the dissolu- 

 tion of that organ; these cells would, therefore, have al- 

 ready possessed a ganglionic nature, and would merely resume 

 in the bud their former function. 



On any such assumption, it is almost impossible to 

 imagine how isolated specific cells, moving freely about in 

 the blood, could reach their proper destination. On the re- 

 verse assumption, hov/ever, the presence of rnesociermal cells 

 at any particular point is accidental, but once there, their 

 potentialities are called out under the specific formative 

 influence of the place of attachment. 



Baltimore, Id., April 18, 1696. 



