216 Field Museum of Natural History -- Reports, Vol. IV. 



its envelopes ruptured, and a third fully developed and discharging 

 its spores; a dense cluster of spores and elaters; the germination of a 

 spore in four stages; and the formation of a young thallus in two stages. 

 The Horsetails (Equiselce) are represented by a reproduction of a sterile 

 shoot natural size; a fertile shoot in spore producing stage; and the 

 beginning of a life history sequence showing, so far, a greatly enlarged 

 section of the female "cone" and the spores in four different states of 

 expansion of the elaters. The staff of the Section of Modeling now 

 comprises the ollowing artists and artisans: A modeler who is chief of 

 the Section, an assembler, a glass worker, a colorist, and a caster 

 and trimmer. The Section has executed a large amount of work during 

 the past year which is embodied in 10 complete reproductions of leafing, 

 flowering and fruiting branches each composed of about 650 separately 

 made parts; 20 separate fruiting branch reproductions and 8 enlarged 

 flower representations comprising an average of 5 separate models 

 each. The following table showing the parts comprising an average 

 "whole plant" reproduction will give an idea of the work required in 

 these assemblages: 



The work of revision of the petroleum collection which was interrupted 

 by the dismantling of the West Annex was resumed during the year hy 

 the Department of Geology and has been carried as near to completion 

 as the limited space at present available will permit. The petroleums, 

 their liquid derivatives and most of the vaselines were transferred to 

 new, tall, oil-sample bottles in which the specimens appear to much 

 better advantage than they did in the old style containers. These 

 bottles have permitted a much more compact installation and thus 

 room has been found for a large number of new specimens of crude 

 petroleums and much material that it was previously necessary to 

 store. The series as now exhibited consists of a large collection of 

 petroleums of the United States, a collection of oil-bearing rocks and 

 associated fossils, a collection of lubricating and other heavy, refined 

 oils, a collection of vaseline and its preparations, a collection illustrat- 

 ing applications of paraffin, some miscellaneous petroleum products, 

 and a quantitative collection illustrating the varied products obtained 

 from refining crude oil. The old order of installation of the petroleums 

 principally according to color has been abandoned and a strictly geo- 

 graphical arrangement substituted. The unit group of this arrangement 

 is the oil field and each group has been provided with a large label 



