410 EVENINGS AT THE MICROSCOPE 



ular heads; if I should nip off one of these heads and flat- 

 ten it by means of the compressorium, you would see it 

 literally composed of cnidce, the ends of which project side 

 by side, as close as they can be packed one against another. 

 But still larger examples may be obtained from the 

 craspeda. With a smart sudden blow I break the stony 

 skeleton of the Madrepore in sunder the flesh 

 tearing apart also; and thus I expose the in- 

 terior of the living animal. A great number 

 of pellucid ribbons are now seen, very much 

 convoluted, which are named craspeda. These 

 are almost composed of large cnidce. 



I remove with fine pliers a small fragment 

 of one of these ribbons, and placing it between 

 the plates of the compressorium, flatten it grad- 

 ually till the plates are brought into as close 

 contact as they can be. A higher power now 

 being put on, examine the organ in question. 

 You see a multitude of perfectly transparent, 

 colorless vesicles, of a lengthened ovate figure, 

 considerably larger at one end than at the other ; 

 one of average dimensions measures in length 

 sfoth of an inch, and in greatest diameter srfooth. 

 CNTDA iSL ADR1Ii ~ "In the larger (the anterior) moiety, passing 

 longitudinally through its centre, is seen a slender cham- 

 ber, fusiform or lozenge-form, about ^Wth of an inch in 

 its greatest transverse diameter, and tapering to a point 

 at each extremity. The anterior point merges into the 

 walls of the cnidce at its extremity, while the posterior 

 end, after having become attenuated like the anterior, di- 

 lates with a funnel-shaped mouth, in which the eye can 

 clearly see a double infolding of the chamber-wall. After 



