2^2 Professor Schweigger (yn the 



matter observed in the cellular substance of plants, especially in 

 the youngest shoots, but which likewise becomes less as the 

 plants advance in growth. This species of coralline can be re- 

 garded therefore only as a marine plant, composed, like many 

 other plants, of distinct articulations, but which gradually as- 

 sumes the appearance of a coral by the deposition of lime in its 

 interior. 



The structure of the other corallines is similar to that of the 

 C. opuntia, excepting that, in proportion as the articulated 

 parts become smaller, the cells are less numerous, and the coral- 

 line is found to consist almost entirely of filaments and calca- 

 reous matter. The Corallina ruhens, Lam. was frequently exa- 

 mined by Schweigger in the Mediterranean, particularly in the 

 Gulf of Spezzia, where he often collected transparent young 

 specimens. These are distinctly composed of parallel filaments, 

 which extend through the joints and digitations without inter- 

 ruption from one end to the other. The delicacy of these young 

 plants did not admit of their being divided by a longitudinal 

 section, which was likewise unnecessary from the branches being 

 sufficiently transparent when examined singly. No trace of the 

 cells of polypi could be detected, nor any resemblance to the 

 structure of those zoophytes which contain polypi. The whole 

 plant may be considered as a petrified conferva, having gradual- 

 ly become consolidated in the course of its growth. The struc- 

 ture of the Corallina officinalis^ which abounds in the Medi- 

 terranean, is similar to that of the C. rnbens, but is more diffi- 

 cult to examine, as it becomes consolidated more quickly, and 

 in a higher degree. Schweigger never found this species trans- 

 parent, but when he immersed it in acids, and examined it un- 

 der the microscope, it exhibited the same kind of structure as 

 the other corallines, though not so distinctly. 



The deposition of calcareous matter in the coralHnes appears 

 to proceed from the surface inwards. The outer covering is 

 observed opaque at particular places, as if incrusted, while the 

 substance within is green throughout, and contains little lime. 

 The calcareous deposition proceeds more and more towards the 

 interior, the green colour and cellular structure disappear ; but, 

 at the commencement of this calcifying process, the vegetable 

 cellular structure can be quickly and distinctly reproduced by 



3 



