ACALEPH^E. 237 



somewhat in the manner of a pocket foot-rule. It is to the 

 combined effect of contraction and the unfolding of the pieces that 

 these lines owe the marvellous changes of length which they 

 present." In Fig. 96 are represented the polyps and fishing-lines of 

 P. hydrostatica, with a portion of the disk and two pairs of repro- 

 ductive, clusters. 



In this figure it will be observed that each fragment or joint has 

 implanted, near the articulation, a secondary line, which bears the 

 stinging organ. Each of these filaments consists of three parts : a 

 straight stem, muscular, contractile, and hollow, the cavity of which 

 communicates with that of the trunk which carries it ; a middle part, 

 a sort of tube containing, in a considerable internal cavity, a trans- 

 parent liquid; finally, an inflated stinging organ, which terminates 

 the apparatus. This last is egg-shaped, and consists internally of a 

 hyaline substance of cartilaginous consistence, in the interior of which 

 we find a great cavity, which opens from within, near the base of the 

 capsule ; to the inside of this cavity a second muscular sac is attached 

 all round the opening of the capsule, in such a manner that the 

 opening leads directly into the cavity of the sac. This cavity conceals 

 in its interior a long filament usually rolled up in a spiral, as illus- 

 trated in Fig. 97, where the two urticant capsules of the stinging 

 apparatus of Physophora liydrostatica are represented, one of them 

 being a section, magnified by twelve diameters. This spirally 

 rolled-up filament consists of a large quantity of very small, hard, 

 sabre-shaped, corpuscular bodies, supported the one against the 

 other, and having their points turned inwards. These objects Yogt 

 terms "urticant sabres:" the extremity of the filament consists 

 of curved corpuscles, larger, of a brownish yellow, very strong, 

 and with a double point. M. Yogt had also opportunities of 

 observing the action of these stinging capsules. He has seen them 

 burst naturally, and he has also obtained artificially the same result. 

 In the former case the filament issues from the opening left at the 

 base of the capsule with a sort of explosion. "The use," he says, 

 " of the fishing-lines becomes evident when we see a Physophora in 

 repose in a vase large enough for its full development ; then it takes 

 a vertical position ; the lines elongate themselves more and more, by 

 unfolding one by one the secondary lines with stinging capsules, and 

 the Physophora now resembles a flower posed upon a tuft of roots, 



