Mo BOTANICAL GAZETTE [February 



some 



— 7 _ M ^. WW , 

 by the exit of the plumule. 



A second detail in which this description must differ from the 

 one cited is that the usual number of cotyledons is only two. They 

 never wholly emerge from the seed. 



common 



forms a sheath about the plumule, is soon ruptured in many places 

 by the radial growth of the latter, and its decay causes the seed to drop 



r 



away 



zami 



Microcy 

 Chamberlain (3), examined 



'luring the period between fertilization and germination, indicates 



time 



to dry, the embryos are killed. Land (io) relates that he has reason 

 to suspect the same condition in Ephedra. 



Caldwell has called attention to the adhesion of embryo to enclo- 



perm 



studied, except Zamia. So intimate is the union, that by using ordi- 



carrres 



them 



and stains with sections of the embryo. 



Coincident with the close adhesion of embryo to endosperm is the 

 remarkable fusion of the cotyledons. Although these always ari, 

 as two distinct organs, the fusion in older embryos is so complete 



JT'Z WCre SeCti ° ned from the apex to within a distance of 



o. 5 above the tip of the plumule without discovering any trace of 



^characteristic seam made by the meeting of the adaxial epidermal 



ayers {fig j). The epidermal cells themselves disappear in many 



cases slightly above the meeting of the inner faces over the plumuh 



™h SCam Tf S n0t S6en t0 extend t0 thc surface at any level in the* 

 embryos, although there were conspicuous superficial sutures (fig. ') 



IT' Cm - The P lumule is derated by the splitting of the 



cotvL t^' CaCh ° f Which simulat ^ the petiole of an individual 

 has' not K* my knowled S e so complete a fusion of cotyledons 



has not been reported of a cycad. 



collated C ° ty !f 0n may have ei S ht or ten vascular strands; all are 

 imm d ! M " k n0Fmal ° rientatio *- Apparent exceptions may occur 

 immediately above a dichotomy or immediately below a fusion or an 



