170 The Ottawa Naturalist. [Dec. 



thus the coleoptile becomes situated at some distance from the 

 cotyledon, as if it represented the first leaf of the seedling. If 

 this be really the case we would have two leaves (cotyledon and 

 coleoptile) situated at the same side of the axis, above each 

 other, and such arrangement of leaves would not be very prob- 

 able. A like structure is exhibited by Rhynchospora alba, Vahl. 

 (Fig. 12), but in this the primary root does not develop at all, 

 being replaced by three secondary roots. The structure of the 

 cotyledon, however, is the same as in Cyperus; inside the 

 coleoptile is the first green leaf from the axil of which a long bud 

 has developed, provided with a smah, adonsed fore-leaf, thus 

 representing the first ramification of the young plant. 



In the CyperacecB we have thus the same structure of the 

 absorbing portion of the cotyledon, while the coleoptile is much 

 further developed than in the third and fourth type described 

 above. The generally adopted explanation of the coleoptile is 

 that it merely represents the sheath of the cotyledon, and in 

 cases where a stem-like organ is developed, in Fuirena,ior instance, 

 this organ is defined as a node, but as a node that has become 

 unusually stretched. It deserves notice, however, that a root 

 sometimes develops from this "node," while roots evidently but 

 very seldom develop from the nodes, but from above or below 

 these. The greatest difficulty by considering the coleoptile as 

 an independent leaf, the first of the seedling, depends of course 

 upon its position, since it is placed on the same side of the axis 

 as the cotyledon ; to overcome this difficulty some authors have 

 expressed the opinion that a leaf is lacking,' and this leaf should 

 then be the small, lobe-like organ "epiblast" so very character- 

 istic of certain genera of GraminecB; this organ is in these 

 situated opposite the cotyledon, and below the coleoptile, thus 

 the arrangement of these three organs would correspond very 

 well with that of normal leaves. But, so far, the epiblast has 

 not been detected in any member of the Cyperacece. 



Now, in regard to the GraminecB, the structure of the em- 

 bryo is very compHcated, and has been the subject of an extensive 

 literature from the hands of a number of the most notable 

 morphologists. But so different are the views expressed that 

 the only point which seems settled beyond doubt is that the 

 Graminece have at least one cotyledon ; some authors think they 

 have two. 



Let us, however, examine a few of these embryos before 

 we review the various explanations that have been offered. On 

 the accompanying plate (Plate IV) I have figured some germina- 

 ting grains of Secale and Zea (Figs. 13-17), and in these we notice 

 the following organs: the primary root (R) with its sheath, the 

 so-called coleorhiza, and frequently accompanied by one or 



