94 ARTHUR BOLLES LEE. 



readiness with certain stains, namely, methyl green, dahlia, 

 gentian, methylen blue, and hsematoxylin. The stain obtained 

 by the first three of these reagents is not of the normal colour; 

 it is a reddish purple. It takes effect with the greatest energy on 

 the distal portions of the hairs, the basal portions being hardly 

 affected by it (except in the case of an over-stain with hsema- 

 toxylin). The hairs are from 0-5^ to Iju thick, and from 

 120/i to 150^ long. 



The aspect of the claviform appendage is totally changed in 

 stained preparations. The fine outer contour described as 

 visible in living specimens is in many examination media quite 

 invisible. If visible in balsam or damar preparations it is in- 

 variably greatly shrunken, generally to a far greater extent 

 than is shown in fig. 3. On the other hand, such preparations 

 reveal the presence of a lumen much narrower than could be 

 suspected from the examination of living specimens. It is of 

 approximately equal diameter throughout the length of the 

 appendage, measuring about 4^/ in general ; so that the walls 

 of the appendage, instead of being almost immeasurably thin, 

 have a thickness, in the living state, of 4ju to 5/x or more. In 

 very shrunken specimens they are practically indemonstrable, 

 and the whole appendage appears reduced to the state of a 

 mere whip, consisting of the sense-hairs and the boundary of 

 the lumen. 



The lumen does not pierce the wall of the appendage at its 

 tip ; there is no trace of any terminal pore. 



The sense-hairs are inserted into the wall of the appendage 

 at the extremity of the lumen. They generally merge insen- 

 sibly into the substance of the wall, though a slight cone or 

 swelling may sometimes be detected at the point of insertion 

 {t.s.h. in fig. 3). 



Ussow does not seem to have seen the true lumen, and seems 

 to conceive of the sense-hairs as floating freely in a thin-walled 

 vesicle represented by the outer contour of the appendage. 



I have not been able to discover the organ either in the 

 solitary form — S. democratic a, or in any other Salpa. 



In the explanation of his figure Ussow calls the organ 



