166 Mr. Dickie on the Reproductive Organs of the Lichens. 



filaments of Greville . contained in the globules of Chora, pos- 

 sess all the physical characters of starch globules; and although 



on account of their very small size 1 have been unable hitherto 



to ascertain satisfactorily the action of iodine upon them, still 

 it is very probable that they are grains of fecula. The lichens 

 which are placed still lower also contain starch, their thallus 

 is the part to which it has been supposed to be confined, but 

 even in this part it does not seem to be of universal occur- 

 rence, since I have been unable to detect it in the thallus of 

 Collema and Bceomyces as specimens; however, if all the genera 

 have not been tested, these are probably not the only two 

 which do not contain it. But the reproductive organs of the 

 lichens also contain a substance which is tinged blue by iodine. 

 The thecae or tubes which contain the sporules are the parts 

 referred to. 



The accompanying figure represents one of the 

 thecae (t) of Pertusaria communis ; it consists of '. 

 a fine transparent membrane, capable of being 

 tinged blue by iodine, and containing in its inte- 

 rior a fluid matter in which the sporules (.9, s) are 

 immersed. Each sporule consists of a membrane 

 similar to the thecae, but not capable of being 

 tinged blue by iodine like it. In the interior of 

 each sporule there is a fluid in which numerous 

 small globules are seen ; they do not seem to 

 possess any constant form. It has been already remarked, 

 that iodine does not strike a blue colour with the thallus of 

 Boeomyces or Collema ; in the latter however the thecae are 

 tinged by it, but in the former there is no blue colour pro- 

 duced in any part. If the action of iodine entitles us to infer 

 the presence of starch, the thecae of the lichens must be con- 

 sidered a peculiar modification of it. From the investigations 

 of Raspail, it appears that each starch globule has the power 

 of producing in its interior other smaller globules, and that 

 these last are (at one period) attached to the inner parietes of 

 the mother cell. 



Perhaps the thecae of a lichen may be considered as a glo- 

 bule of starch of a peculiar form, in the interior of which 

 other globules are produced, the sporules namely. I have not 



