1877 WOEK ON MEDUSA 61 



form of a pair of trousers, in such a way that a 

 ganglion, a, occupies the bottom of one of the legs. 

 Usually, of course, contractile waves starting from 

 a course along to b, and thence round to c and 

 backwards to d. But in one specimen I observed 

 that every now and then the exact converse took 

 place — viz. the contractile wave starting at d to 

 course to c, b, and a. On now excising the 

 ganglion at a both sets of contractile waves ceased 

 ^thus showing that even in the case where they 

 started from d it was the ganglion at a which 

 started them. This power on the part of Medusoid 



a 



777777//?/////////////////////////////////////////////, 



Fig. 3. 



ganglia to discharge their influence at a distance 

 from their own seat I have also observed in other 

 forms of section, and it affords the best kind of 

 evidence in favour of nerves. 



On the days when I could get no jelly-fish I took 

 to starfish. I want, if possible, to make out the 

 functions of the sand-canal and the aviculse ; but as 

 yet I have only discovered the difficulties to be over- 

 come. I had intended to make a cell to cover the 

 calcareous plate at the end of the sand-canal, and to 

 fill the cell with dye, in order to test Siebold's hypo- 

 thesis that the whole apparatus is a filter for the 



