PHYSIOLOGICAL BOTANY. 283 



i, 27. The author describes the papillae and their con- 

 tents, which exist upon the flowers of Chrysanthemum 

 indicum, Thunb. ; he considers them as glands. I do 

 not find it mentioned that these papillae have long since 

 been found and described upon ail true corollas. The 

 blue powder upon the leaves of Chenopodium and Atriplex, 

 is incorrectly referred to them ; it consists of globules 

 of wax. 



On merismatic Formation of Cells in the Development 

 of Pollen. By Dr. F. UNGER; 1844. An excellent 

 memoir in a few pages. " According to my observations," 

 says the author, " the earliest traces of renewed organiza- 

 tion in the mature parent-cells, appear as very thin and 

 delicate streaks, which either run transversely across the 

 centre, or laterally, according to the position of the parent- 

 cell. These streaks, as any one may easily satisfy himself 

 by turning round the parent-cell, are nothing else than 

 extremely thin and transparent walls, which divided the 

 uniform granular matter into several parts. These walls, 

 which must necessarily be formed from the above-men- 

 tioned contents, are so perishable, that they dissolve in 

 water, which renders it probable that they consist of gum. 

 But simultaneously with this phenomenon, a spontaneous 

 separation of the granular mucilage occurs, which espe- 

 cially tends to show that from this moment the nucleus of a 

 cell begins to be developed in each portion. The forma- 

 tion of these walls still proceeds, so that they not only 

 soon acquire greater firmness, but also greater thickness. 

 The first commencement of true membranous development 

 (for the earlier deposit can scarcely be considered such) 

 distinctly takes place from the walls towards the central 

 point. First, there appear projecting ridges, and from 

 these the membranes crystallize, as it were, more and 

 more toward the interior, so that we can trace the progress 

 step by step." Further on : " Hence there are no special 

 parent-cells, separate and inclosed by the parent-cells, but 

 only special parent-cells which originate as divisions of 



