DEVELOPMENT OF THE MICROSPORANGIA AND 

 MICROSPORES OF ABUTILON THEOPHRASTI 



- 



V. L A N T I S 



(with twelve figures) 



The material used in this study was collected during September 

 and October 1910. While many killing and fixing fluids were 

 tried, Flemming's weaker solution proved the most satisfactory and 

 was therefore the most generally used. 



Because of the excessive development of sclerenchymatous 

 tissue in this form, much difficulty was first experienced in sec- 

 tioning. This was obviated, however, by infiltrating and imbed- 

 ing in Johnston's paraffin-asphalt-rubber mixture (11, 16), which 

 consists of 99 parts of paraffin (desired grade) in which has been 

 melted enough asphalt (mineral rubber) to give the paraffin an 

 amber color, and one part of crude india rubber. This method, 

 in that it has proved so satisfactory, deserves a more general 

 use among botanists. Many stains were tried, but Heidenheim S 

 iron-alum hematoxylin, with orange G as a contrast stain, gave 

 the best results. 



The stamens of Abutilon Theophrasti Medic, are epipetalous, 

 monadalphous, and branching. Occasionally the branches of the 

 filaments are so short that the two anthers set back to back, and 

 the two might be taken for one anther in a hasty examination. 

 In longitudinal section the anthers are more or less crescentic 

 in form, while a cross-section shows them to be two-rowed (fig. 5)- 

 In this respect it is very much like Althaea rosea Cav. (2, 4) and 

 Tilia ulmifolia (7). It is not at all uncommon to see one lobe 

 much longer and more crescentic than the other. The filament is 

 attached to the middle of the inner side of the crescent-shaped 

 anther. Dehiscence takes place by means of one longitudinal 



fissure. 



in eacn anuici, 



one in each of the two lobes. With resDect to the number of 



Botanical Gazette, vol. 54] 



[33° 



