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Botany. — "On a case of apogamy observed untJi Dasylirion 

 acrotrichum Zucc." By Prof. F. A. F. C. Went and A. H. 

 Blaauw. 



In the summer of 1904 a specimen of Dasylirion aerotrichiim Zucc. 

 was in bloom in the Utrecht Botanical Garden. Tiie home of this 

 tree-like Liliacea is in Mexico ; on a short stem it bears a bundle 

 of flat leaves with thorny margins. Although the plant is pretty 

 often cultivated in European botanical gardens it is Aery seldom seen 

 in bloom. Hence constant attention was paid to the here mentioned 

 specimen. The inflorescence was two metres long ; the principal axis 

 was ramified and had a great number of steeply erected lateral axes 

 in the axils of bracts ; each of these carried some 50 to 150 

 unstalked female flowers. Dasylirion is dioecious so that male flowers 

 were entirely absent. 



Each flower had a perianth consisting of six green leaflets and a 

 pistil ; this latter consisted of a triangular ovary with a short style 

 and three stigmas. The ovary was unilocular and had on its bottom 

 three ovules. 



After the flowers liad finished blooming it seemed as if some 

 ovaries began to swell. As there could be no question of fertilisation 

 in the absence of male sexual organs, it was thought that perhaps 

 a new case of apogamy or parthenogenesis was present here. The 

 ovaries were now regularly examined ; they more and more assumed 

 the appearance of little fruits, looked like small nuts provided with 

 three wings and strongly reminded one of the fruitlets of Rheum. 

 It appeared that many ovules swelled, but never more than one in 

 each ovary. Not nearly in all flowers this phenomenon was observed, 

 in no more than 10 to 40 percent it was at all visible. 



For a detailed investigation these ovules were now fixed in 

 FijEmming's fixing solution (the weak solution) and then washed in 

 the usual manner and gradually placed in strong alcohol. This was 

 done for the first lime on August 15 ; from 158 ovaries 49 ovules 

 were obtained, i.e. 31 percent. This was a maximum, however, for 

 when later material was collected in the same way on August 22, 

 September 3, 10, 13, 19 and 25, October 8 and 22, November 12, 

 December 15 and 24 and on January 19, 1905, each time more and 

 moi"e ovules appeared to be unfit for use, as they began to wrinkle. 

 Such as looked more or less swollen were fixed ; among these some 

 had grown thicker and finally the impression was that some seeds 

 had ripened. But ultimately not a single germinable seed appeared 

 to be on the plant and after January 19 no material fit for investi- 



