xm] SPINNING APPARATUS AND FEET 113 



other or against the sides of the tube. The anteriors 

 and posteriors, moreover, are two-jointed though 

 the medians consist only of a single joint. 



So much can be seen without any great magnifi- 

 cation, but the microscope will be necessary if a 

 complete understanding of their mechanism is to be 

 arrived at. What it reveals will now be briefly 

 described, and will, it is hoped, be made tolerably 

 clear by the accompanying figures which are simplified 

 by the omission of a large number of bristles which 

 tend to hide the essential structure, and by a great 

 reduction in the number of "spools," though the 

 spigots are all indicated. 



The anterior spinneret (that nearest the head end 

 of the animal) is a sort of cone, divided into a large 

 basal joint and a small terminal joint. The latter 

 bears on its inner side a single spigot (fig. 1 2 a) and 

 is crowned with a battery of spools, about a hundred 

 in number. 



The median spinneret has three spigots, two at 

 the tip and one on the inner side (fig. 12 &), and about 

 a hundred spools, mostly on its inner surface. 



The posterior spinneret is divided very obliquely 

 into two joints, so that the terminal joint extends 

 much lower down on the inner than on the outer 

 side. It has five spigots in groups of three and two, 

 and again there are about a hundred spools. 



Now the point that I wish to make clear is that 



w. s. 8 



