552 1. IKEDA : 



to nie more i)ro1)a])le' that these appearaiiecs were caused simply 

 by the juxtaposition of intersecting fibres. 



The nerve endings in tlie preoral ciliated Ijclt deserve special 

 notice. In fig. (30«, there is shown a row of small dots alonir 

 the margin of the band. A portion of the latter more highly 

 magnified is shown in fig. (10 A. Here each fibre ends in a small 

 knob wliich is devoid of any lateral process. At first sight luider 

 l(jw magnification, the row of knoljs appears like a deeply stained 

 ring. Huspecting that there might exist lateral processes connect- 

 ing knobs, I have repeatedly made observations and experiments, 

 but without having ever been able to demonstrate such a connec- 

 tion between them. 



I can not l)ut thiidc it very strange that post-ganglional nerve 

 fibres, if such really exist in the forms of the collar ring and of 

 the dorsal and the ventral commissures, should not be revealed l)y 

 the method ado])ted. The negative result may be considered due 

 to incomplete develo})ment of nervous elements in the collar and 

 in the trunk region ; but other anatomical relations prove to a 

 certainty that the larvie investigated were fully grown. ^Vs I am 

 not (juite sui'e that my method was not in some respect im])erfect, 

 1 leave the matter undecided for the present. 



According to ]\Iasterman, there is an ectodermal depression 

 directed inwards and backwards, just in front of, and under, the 

 ganglion. He calls it the " neurojwre," comparing it to tlie 

 neuropore of Ami^liio.uis and even to the medullary canal of 

 Vertebrates. I nmst say 1 was much disappointed in failing to 

 detect in the ActinotrocJuc studied by me this structure of so nmcli 

 theoretical interest. As a matter of fact, it happened very fre- 

 quently, while ol »serving livhig larvjc, that tlie ganglion was 

 retracted dee})ly inwards by an active contraction of the two 



