THE COELOMIO FLUID IN ACANTHODRILIDS. 577 



minute concentric fibrils ; and moreover, the refringency is 

 not limited to the outline of the inclusion, but crosses the 

 " vacuole" in curved lines, each of which presents the same 

 appearance of fibrillation, and, as one focusses this strange 

 inclusiou, the whole resembles a coil or tangle of cotton. 



The use of certain reagents renders the thread more dis- 

 tinct, and separates the fibrils from oue another, so that the 

 tangle appears to be unravelled before oue's eyes (see fig. 25) ; 

 but I have failed, after long search, to detect a free end ; 

 nor is there any regular spiral arrangement such as both 

 Goodrich and Eisen have indicated. 



Whereas the majority of the cells have but one such " coil 

 of thread," a few cells (or in one specimen, at least, the 

 majority of the cells) contain several threads, which are of 

 different sizes and degrees of development. Thus, on July 

 11th I noted a great variety in the form of the coil, as these 

 figures well illustrate (see figs. 18, 19, 20). One particularly 

 curious cell is figured (fig. 21) ; it shows two coils, a circular 

 and an hour-glass shaped one, which is further represented 

 enlarged at the sides, But generally, in the case of the 

 several small " coils," each lies in one plane, is simple, and 

 more or less circular ; whereas, in the case of what I think 

 may be regarded as normal linocytes, the "coil" is sphe- 

 roidal, and complicated by crossings and " intertwinings " as 

 it were. 



From a series of observations, made at two different 

 seasons of the year, in worms of different degrees of sexual 

 maturity I have been able to trace the development of this 

 curious cell-product. 



The linocyte is at first a spherical, colourless, non-amoe- 

 boid cell, filled with cytojdasm only, and bounded by a 

 delicate but distinct membrane (tig. lU). 



The cytoplasm is very finely granular, and is occupied by 

 numerous very small, circular vacuoles, so regularly arranged 

 as to deserve the descriptive term "honeycomb." The 

 nucleus, even in the younger cell noted by me,^ is peripherally 



' it is prubable that a still earlier phase of tliis liuocyle bears some rela- 



