718 Mr. Beown on the Organs and Mode of 



and Schreber, respecting the structure of the stamina and stigma. 

 With this view I appealed to the remarkable fact, that in the 

 early state of the flower-bud the pollen masses are absolutely 

 distinct from the glands and processes of the stigma, to which 

 they in a more advanced stage become attached. This proof of 

 the real origin of parts I then believed to be entirely new. It 

 has however been already seen that the fact was noticed by 

 Gleichen, and it will presently appear that it was also well 

 known to another original observer. 



In the essay referred to, I had not very minutely examined 

 the texture of the pollen mass, and in true Asclepiadeae I had 

 failed in ascertaining its real internal structure ; not having 

 been then aware of the existence of the included grains of 

 pollen, but believing, until very lately, that the mass in its 

 most advanced state consisted of one undivided cavity, filled 

 with minute granular matter mixed with an oily fluid ; and 

 hence concluded that the fecundating matter was conveyed 

 from the mass through the arm and gland to the stigma. 



In the month of April last I saw, for the first time, draw- 

 ings of several Asclepiadeae made between 1805 and 1813 by 

 Mr. Bauer, who, aware of the interest I took in this subject, 

 with his accustomed liberality and kindness, offered me any 

 part of them for publication. 



Among these drawings, exceeding perhaps in beauty and 

 in the completeness of the details all the other productions 

 with which 1 am acquainted even of this incomparable artist, 

 an extensive series, exhibiting the gradual development of the 

 parts of the flower in Asclepias curassavica, were the most 

 important. 



In this series, made in 1805, and commencing when the 

 pollen is just separable in a pulpy mass from its cell, the 

 glands of the undivided stigma being still invisible, the fact 



of 



