420 cook: seedling morphology 



3. Decomposition of molybdates, the explanation offered 

 for the formation of ilsemannite from wulfenite at Bleiberg, 

 Carinthia. 



4. The decomposition of a molybdenum-bearing silicate, 

 such as molybdosodalite. 6 



The analysis of ilsemannite from Utah shows a percentage of 

 2.37 Mo0 3 for the sample of rock taken. Other samples showed 

 only about half as much molybdic oxide, but the average per- 

 centage of water-soluble molybdenum contained in the rock as a 

 whole is not known. 



BOTANY. — Seedling morphology in palms and grasses. O. F. 

 Cook, Bureau of Plant Industry. 



Morphological interpretation of the grass embryo has developed 

 a voluminous and highly technical literature, a recent contri- 

 bution being a paper by Worsdell on The Morphology of the 

 Monocotyledonous Embryo and of that of the Grass in particu- 

 lar. 1 



From the standpoint of the palms, the effort to interpret the 

 first leaf-sheath of grasses, the so-called coleoptile, as a part of 

 the cotyledon appears artificial and unnecessary. Worsdell 

 carried this idea to the extreme of identifying the coleoptile with 

 the ligule of a very highly specialized cotyledonary leaf, the 

 nursing foot, or scutellum, with the blade, and the epiblasts with 

 auricles of the blade. 



Comparison with the germination of the palms would make 

 such assumptions unnecessary. It is possible to interpret the 

 seedling organs of palms in simple terms of general morphology 

 that writers on grasses leave out of account. The grass em- 

 bryo has its specialized features, but there can be no advantage 

 in undue elaboration of the differences. 



THE PLANT BODY METAMEROUS 



The general fact to be kept in mind is that plant bodies are 

 metamerous, that is, made up of phylogenetically and mor- 



6 Described by Zambonini, F. Mineralogia Vesuviana, p. 254. 1910. 

 1 Annals of Botany, 30: 509-534. October, 1916, with bibliography. 



