166 BOTANICAL GAZETTE [august 



known because the economic value of coal has uncovered immense areas; 

 while the Permian, Rhaetic, or Middle Triassic have depended upon the 

 enthusiasm of about a dozen scientists. The flora of these horizons is probably * 



as abundant and varied as that of the Carboniferous, but not so available. 



In going back through the geological horizons, there is a gradual merging 

 of Coniferophyte, Cycadophyte, and Ginkgophyte foliage toward seed- 

 bearing " quasi-ferns." Also tow r ard the early Paleozoic there seems to be ? 

 some kind of contact between the early seed ferns and the older Lepidophyte J 

 types leading toward the primitive Gymnosperms. Whether well down in 

 the Devonian some of the Lepidophytes, like the later seed ferns, may also 

 have led into the primitive Gymnosperms is the real riddle of paleobotany, 

 more so than the origin of Angiosperms. In almost all instances the doubtful 

 border of Cycadeoid foliage ends in a tree forest of seed ferns, Cordaites, 

 pines, araucarians, and Ginkgoes, but never in a recognizable scrub. It is 

 stated that among the Cycadeoids will be found the lost forests and the greatest 

 forest makers of the Mesozoic. 



Wieland suggests that from age to age great groups have come down side 

 by side, undergoing endless change and losing apparent relationships ; but almost 

 no forms, scarcely a family, need be regarded as more ancient or more modern 

 than any other. It is conceivable that all the antecedent types of Angiosperms { 



are discrete separate lines leading back to the first forests of the Devonian. — 

 J. M. C. 



History of cotyledony. — Buchholz, 10 in connection with his studies of 

 embryo development in conifers, has reached certain conclusions in reference 



primitive 



His 



investigations showed that in a number of conifers fusions of cotyledons occur 

 during embryogeny, and that there is no evidence of splitting. Fusion results 

 not merely in a reduced number of cotyledons, but 6ft en in the development 

 of cotyledonary tubes. The conclusion is that the primitive gymnosperm 

 embryo had numerous cotyledons ; that fusions resulted in a reduced number ; 

 that dicotyledony was attained either by a fusion of cotyledons into two 

 groups or by an extremely bilabiate development of a cotyledonary tube; 

 and that monocotyledony is the result of a cotyledonary tube becoming 

 "unilabiate" in its development. According to these conclusions, therefore, 

 polycotyledony is primitive, dicotyledony is derived, and monocotyledony is 

 the extreme expression of cotyledonary fusion. — J. M. C. 



Life cycle of climbing bamboo. — Seifriz 11 has published some observa- 

 tions on one of the climbing bamboos (Chusquea abietifolia) growing in Jamaica. 



10 Buchholz, J. T., Studies concerning the evolutionary status of polycotyledony. 

 Amer. Jour. Bot. 6:106-119. figs. 25. 1919. 



11 Seifriz, W., The length of the life cycle of a climbing bamboo; a striking case of 



sexual periodicity in Chusquea abietifolia Griseb. Amer. Jour. Bot. 7:83-94- fii s - 5- 

 1920. 





