SALPJE THEIR AGGREGATION AND LUMINOSITY. 435 



reach. These were found, on examination, to consist of minute 

 Salpae, each not more than two or three lines in length, aggre- 

 gated together in bands. The colour was given by their nuclei, 

 which did not exceed millet-seeds in size. These bands are 

 driven through the ocean by the action of the waves ; and they 

 seem to have a remarkable power of preserving their continuity, 

 even when a considerable force (for animals of such delicacy) is 

 applied to separate them. In fact, the connection is so strong in 

 some species, that it is easier to tear the animals themselves than 

 to part one from another ; although their union is accomplished 

 only by the adhesion of their surfaces, or of little suckers, adapted 

 to meet each other, and not by any structural connection. In 

 other species, the adhesion is less powerful ; so that when a mass 

 is placed in a vessel of water, and the sides of it are smartly 

 struck, the individuals fall asunder. 



1069. Nearly all the Salpce are phosphorescent, or self-lumin- 

 ous ; and the small aggregated forms are usually more so than 

 the large isolated ones. The bands which they form are, conse- 

 quently, among the most brilliant of those luminous tribes, which 

 occasionally give such a sparkling lustre to the waters of the 

 ocean. The Salpae, when thus chained together, produce the 

 effect of long ribands of fire, sometimes drawn straight in the 

 direction of the currents, sometimes twisted and almost doubled 

 by the action of the waves. 



