346 EVENINGS AT THE MICROSCOPE. 



tossed wildly upward, and then waved downward, as if to 

 mimic the actions of the most tumultuous human passion. 



Whenever the Sabella protrudes from its tube, these 

 guardian forms are pushed oat, and remain nearly in con- 

 tact with the Annelid's body, moving but slightly ; but no 

 sooner does it retire than they begin instantly to bow for- 

 ward and gesticulate as before. These movements are 

 continued, so far as I have observed, all the time that the 

 Sabella is retracted, and are not in any degree dependent 

 on currents in the surrounding water, whether those 

 currents be produced by the action of the Annelid or by 

 other causes. They are not rhythmical ; each individual 

 appears to be animated by a distinct volition. 



Applying a higher magnifying power than we have yet 

 used to the animals, we find that the head-lobe incloses a 

 central cavity ; that the arms are also hollow, with thick 

 walls, marked with transverse lines, indicating flattened 

 cells, and muricated on the exterior ; and that the body 

 contains an undefined somewhat opaque nucleus, doubt- 

 less a stomachal cavity. 



I cut out, with fine scissors, a segment of the tube, 

 including two of the parasites, with the portion of the 

 network of threads that carried them. They have become 

 immediately paralysed by the division of the threads, but 

 those that remain on the tube are unaffected by the 

 violence. Subjecting one of the animals so cut out to the 

 action of the compressorium, with a power of 560 dia- 

 meters, the arms are seen to be formed of globose cells, 

 made slightly polyhedral, or many-sided, by mutual pres- 

 sure, set in single series. The interior of these organs 

 is divided by partitions, placed at intervals of about the 

 diameter. Some at least of the cells contain a small 

 bright eccentric nucleus. 



When the tissues were quite crushed down by the pres- 

 sure of the compressorium, a quivering motion was visible 

 among the disjointed granules, but it was very slight. 



