4M 



BOTANICAL GAZETTE 



[JUNE 



the size of the cotyledons of Encephalartos Barteri. Bower (8) recorded 

 a difference in the size and anatomy of the two cotyledons of Cycas Seemanni; 



and Land (Chicago) has noted 

 (unpublished) a difference in the 

 size of the cotyledons of Zamia 

 integrijolia. 



Outside the cycads one finds 

 the same tendency in seeds of 

 similar habit. Solms-Laubach 

 (9) figured it in an embryo of 

 Bennettites Gibsoniana, a fossil 

 relative of the cycads; and 

 Coulter and Chamberlain (10) 

 and Lyon (ii) have recorded it 

 of Ginkgo. 



In the course of my ana- 

 tomical study, I noticed that 

 the cotyledon was a lateral 

 structure and that there was 

 absolutely no external trace of 

 another (fig. j), but certain 

 irregularities in the vascular sys- 

 tem made me suspect that the 

 second cotyledon had been sup- 

 pressed. These irregularities con- 

 sisted mainly in the suppression 

 of one pole of the root, and the 

 presence of certain rudimentary 

 strands which joined the stem 

 in normal fashion, but whose 

 upper portions ended blindly in the cortex or fused with other bundles. 

 The suspicion was strengthened by the observation that in every case 

 the cotyledon developed on the under side as the seed lay. This latter 

 circumstance led me to think that gravity was responsible for the 

 monocotyledonous condition. 



In the following autumn, therefore, fresh ovules were placed in broad 

 pots, covered closely with sphagnum, and placed upon clinostats revolving 

 at different rates of speed. In December the Livingston porous cup 

 apparatus (12) was inserted in order to equalize the soil moisture. At the 

 same time fresh seeds were planted in the greenhouse. 



Figs. 4 and 5. — Embryos developed on 

 clinostat; removed February 3. X8. 



Fig. 6. — Cross-section of middle region 

 of cotyledons of an embryo removed from 

 clinostat February 26. X8. 



Fig. 7. — Embryo taken from soil in 

 green house January 8. XS. 





