36 



ZOOPHYTES. 



Actinia is very large. When the animal is contracting, they are 

 often protruded in folds from the month, having come up from the 

 visceral chamber, through the stomach (plate 2, figs. 12, 15, 16) ; and 

 if the skin be fractured in any part, they escape in large bunches. 

 These cords are sometimes seen to pass out through the perforations 

 in the sides of the animal ($ 22), as was long since ascertained by 

 Dicquemare.* The same fact was observed in the species examined 

 by Dr. Wyman. 



The white spermatic cords are semitransparent or nearly opaque, 

 and are furnished with vibratile cilia. On subjecting them to slight. 

 pressure between plates of glass, slender filaments extrude, in length 

 a little exceeding half the diameter of the cord ; and, with a high 

 magnifying power, a fragment of the cord thus under pressure pre- 

 sents the appearance in figure 16, exhibiting pellucid spicula, like 



Fig. 16. 



Fig. 17. 



Fier. 18. 



Fig. 19. 



radii to the cord ; the long filaments pertain to the spicula, and were 

 extruded by the pressure. Figure 16 is properly a flattened trans- 

 verse section ; figure 17, a camera lucida sketch, by Dr. A. A. 

 Gould, represents their position, as they were somewhat deranged by 

 the pressure. These spiculiform organs, as observed by Dr. Wyman 

 under one of the best English microscopes, are of three kinds, 

 represented in figures 19 a, b, c. In a, the body is slightly curved 

 and transparent, but with a more pellucid medial line, and the fila- 

 ment is a simple naked thread, two or three times its length. In b, 

 the body is transparent, nearly as in a, but the filament is slightly en- 

 larged through the latter two-thirds of its length, and this enlarged 

 part is bristled, with the bristles reversed ; the extremity moreover is 

 obtuse. In c, the body appears to be filled with granulous matter; 

 the filament is enlarged as in b, but it is lengthened out to a very deli- 

 cately attenuated extremity ; and the enlarged part, which is half its 

 whole length, appeared spotted or chequered. These singular forms 

 were seen frequently in cords taken from many individuals. Besides 

 these organs, he detected minute oval points, with very short filaments, 



Phil. Trans. Abridg., xiii. 639, 1775. 



