﻿THE EMBRYO SAC OF RICHARDIA AFRICANA KTH. 



Margaret R. Micheli 

 (with PLATES xxi-xxiii) 



Up to the end of last century very little was known of the 

 embryo sacs of the different genera of the Araceae. Since then, 

 however, several American botanists have contributed to our 

 knowedge of the subject, with the result that now we do know some- 

 thing of the development of the embryo sacs. Yet in spite of this 

 work, our knowledge of the family is by no means satisfactory. 

 Perhaps this may be due to the fact that much of the material 

 worked upon has been collected in greenhouses, where conditions 

 are far from normal. The difference in habit between the plants 

 of Richardia africana growing in their home in South Africa and 

 those found in greenhouses in England is most striking, and it is 

 possible that conditions which can affect the outward appearance 

 of the plants to such a large extent may be effective in producing 

 abnormalities in the embryo sac. 



While this investigation was in progress, Gow (7) published a 

 short account of the embryo sac of Richardia. His results differ 

 from mine in so many respects, however, that it seems advisable 

 to publish my results, particularly as my material was obtained 

 from plants in their native habitat. 



Richardia africana is a native of Cape Colony and St. Helena (5), 

 and flowers freely in damp open places in the Cape Peninsula, 

 where the material for this investigation was collected. The plants 

 are in full flower in August, although young inflorescences may be 

 obtained as early as April. 



The chief fixatives used were an alcoholic solution of corrosive 

 sublimate and picric acid, made according to Jeffrey's formula: 

 Carnoy's fluid and a mixture of three parts of absolute alcohol 

 to one part of glacial acetic acid. A certain amount of shrinking 

 took place in all cases, though in the very young ovaries fixed in the 

 absolute acetic mixture this was practically negligible. Chrom- 

 acetic solutions gave very poor results. The chief stain used 

 325] [Botanical Gazette, vol. 61 



