250 THE BIOLOGY OF STENTOR 



" beautiful sea-green ". Body cilia beat as long as the ectoplasmic 

 structure remained intact. 



10. Shedding of pigment and pellicle 



The pigment of stentors is largely located in ectoplasmic 

 granules beneath the pellicle where it is often readily affected by 

 external agents. The species which has been studied is coeruleus, 

 observation of which indicates that pigment sloughing may even 

 occur under natural conditions, as was first suggested by Schuberg 



(1890). 



Loss of pigment occurs under three guises. A homogeneous 

 blue-green halo may be ejected, suggesting that the pigment 

 granules have been burst and their contents set free. The granules 

 may be cast off^ as such and appear as tiny particles, which seems 

 to be the case in natural sloughing. And finally, one or more layers 

 of the pellicle may also be shed, and in this case the outer surface 

 carries the granules with it where they remain in rows corresponding 

 to the pigmented stripes. It is surprising that the pellicle can be 

 sloughed without apparently interfering in any way with the cilia, 

 for the outer coating of the cilium is in all ciliates continuous with 

 the pellicle covering of the cell body. This also occurs even more 

 clearly in Blepharisma treated with strychnine in which the 

 animals swim out of the discarded pellicle (Nadler, 1929). As 

 already suggested, pellicular shedding may have been elaborated 

 as a method of case-making, both in certain species of Stentor and 

 in FoUiculina. In the latter, Andrews (1923) found that the form- 

 ing sac at first shows lines of pigment granules corresponding to 

 stripes on the body. An appearance very much like this can be 

 induced in coeruleus which forms no lorica. 



In methylene blue, Neresheimer (1903) produced a separation 

 of the stentor ectoplasm, and it was in this way that he obtained 

 the pieces which he stained to demonstrate " neurophanes ". 

 Much later Weisz (1950a) obtained sloughing of pigment and 

 peUicle in Janus green. 



Prowazek (1904) found that brief immersion of coeruleus in \% 

 NaCl caused a shedding of pigment as a homogeneous blue halo. 

 The coloration was then regenerated in about a day after returning 

 to normal medium. In the same year, Peters (1904) independently 

 made the same observation and carried the study much further. 



