ZOOPHYTES 379 



polypes and organs proper to the complete organism. 

 When this is the case, an admirable opportunity is pre- 

 sented for studying with ease and precision the economy 

 of the creature; and it is to the skill with which Dr. T. 

 Strethill Wright has availed himself of such an opportu- 

 nity 1 that I am indebted for the chief part of the facts 

 that I am going to tell you, connected with the form and 

 appearance, of which you can here judge for yourself. 



The spreading film or polypary is a thin coat of trans- 

 parent jelly, slightly colored with various tints, which se- 

 cretes and deposits within its substance a still thinner 

 horny layer of chitine. This rises here and there into 

 numerous spines and points, which are curiously ridged 

 with toothed keels; and these ridges run in various direc- 

 tions over the horny layer also, making a fine network 

 over it. The investing flesh, however, fills up all the 

 cavities and areas so enclosed. 



The mode in which the polypary increases is by throw- 

 ing out from its edge a creeping band, exactly analogous 

 to the root- thread of the Laomedea. This "propagative 

 stolon, after leaving the point of its origin, increases 

 rapidly in diameter, and sends out irregular branches. 

 The tips of these branches are covered with a glutinous 

 cement, by which they attach themselves tenaciously to 

 glass, or other surface near them. Having attached them- 

 selves, they expand laterally, at the same time throwing 

 out finger-like prolongations, which, as they come in con- 

 tact with each other, coalesce, until a fleshy plate is found 

 adherent to the glass. Polypes are developed both from 

 the loose branches and the attached polypary; and the 



1 See "Edin. New Philosophical Journal," for April, 1857. 



