INTRODUCTION. xli 



participate in this change ; and the account which fol- 

 lows will supply the grounds on which I have abandoned 

 my former views on this subject. 



It must, I think, be admitted that the interpreta- 

 tion first suggested by Fritz Miiller was founded rather 

 on mere superficial resemblances and the supposed fitness 

 of things than on any thorough investigation of the 

 structure and functions of the so-called nervous system. 



Nitsche, after a careful examination of the tissue in 

 question, decides against that interpretation*. Reichert 

 has given us an elaborate account of it, and has pointed 

 out the important fact, that the supposed ganglia are 

 cut in two by the septa, which separate the intemodes 

 from each other and close the zooecia below. He holds 

 that the tissue is not nervous in character f. 



But by far the most important contribution to our 

 knowledge of this element of polyzoan structure has 

 been made by Joliet. It is not in the slightest degree 

 to detract from the merits of this most able observer to 

 say that further investigation is required before some of 

 his conclusions can be finally accepted. But so far as 

 the general nature of the funicular system is concerned, 

 his testimony seems to me to be conclusive. 



I am unable to enter here into the detail of his ex- 

 haustive researches. I shall merely indicate briefly the 

 characteristics of the tissue, which, in my judgment, 

 are incompatible with Muller's theory. 



i. Its intimate structure; the form and behaviour of 

 the cells composing it are not those of a nerve-tissue. 



The cells are normally fusiform (Woodcut, fig. xvi.) ; 



I i-b. Vluttra mtmhranucra. W. cit. p. 56. 



t Abhaudl. Ak. Berl. 1*70, phvsikalische KUw*. 



