POLLEN. 



Two years ago Mr. Airey published some interesting facts 

 about the dust collected on smeared plates of glass, and 

 mentioned that some of the dust was pollen. I began ac- 

 cordingly to enquire into the forms of pollen likely to be 

 found in such places, and from this went on to discover all 

 that I could about pollen. I had many years ago drawn a 

 number of specimens, but I now took to examining them 

 more closely, and drawing them to scale. 



The principal papers already published on this subject 

 are by 



1. Purjinke, in Latin. His illustrations of the cells of 



the anther are very interesting, but unfortunately, 

 the pollens drawn have been treated with water, so 

 as to lose most of their distinguishing marks. 



2. By Mirbel, in French. Accurate as far as they go, 



but on too small a scale. ( f Siemens de Physiologie 

 vegetale,' 1815.) 



3. By Fritzsche, in German (1832). Most beautifully 



drawn both in the simple form and under oil, and 

 under the effects of weak sulphuric acid. He 

 examined almost all the natural families. 



4. By Hugo Mohl, in German, translated into French in 



the 'Annales des Sciences Naturelles.' He goes 

 most thoroughly through all the families in the 

 natural state of the pollens, or as they appear under 

 olive oil or water ; drawn to scale. I have followed 

 in his footsteps ; and now I wish to point out a few 

 inaccuracies into which he has fallen, and to carry 

 on the examination of the other plants. 



5. Hassall reviewed Mohl, showing some differences, and 



