105 



and Ox]\c;rapliis Cynibalaria {V\xvi=,\\) Prantl. The work was done 

 at the suggestion of Professor Francis Ramaley. 



The cotyledons in the four species examined are all more or 

 less ovate in outline, being of the usual Ranunculaceous type. 

 The leaves in the first three species are much cut and divided 

 while in Oxygt-apJiis they are cordate-ovate with much branched 

 veins. In no case does the cotyledon resemble the leaf in form. 

 In O.vygrap/iis Cynibalaria the cotyledon-stalks arc connate from 

 their bases almost to the blades. 



No constant difference of striking character was noticed in the 

 epidermis of cotyledons and leaves. However, it was seen that 

 the number of stomata was much smaller for a given area of 

 cotyledon than for a similar area of leaf surface. No stomata 

 were seen in the upper epidermis of either leaf or cotyledon of 

 Aquilcgia cocrulca. " Twin stomata," i. e., stomata in contigu- 

 ous pairs, were seen in the lower epidermis of both leaf and coty- 

 ledon in this species. In the literature at hand there seems to 

 be no mention of this peculiarity as having been noted in Ranun- 

 culaceae. Long, simple hairs occur on the under surface of the 

 cotyledon of Pulsatilla hirsutissima and on both surfaces of the 

 leaf. 



In the internal structure of leaf and cotyledon the one-row 

 palisade is characteristic of all, the single exception is the coty- 

 ledon of OxygrapJiis in which the palisade might be described as 

 two-layered. The spongy tissue of the cotyledons corresponds 

 to that of the leaves, especially in the shape of the cells and in 

 the size of the air-spaces. The vertical sections, excepting in Pul- 

 satilla hirsutissima, showed about the same thickness, but in that 

 species the cotyledon was about twice as thick as the leaf. This 

 difference in thickness is brought about by the greater size of the 

 cells in the cotyledon. 



The leaf-petioles are quite different from the cotyledon-stalks 

 in the four species. Figures i to 8, which are diagrams of cross- 

 sections, show these differences* plainly. In each case the leaf- 

 petiole is somewhat cylindrical with about three vascular bundles 

 while the cotyledon-stalk is more flattened and has only a single 

 small bundle. Figures i and 2 are oi Aquilcgia cocrulca, ^'gwxcs 



