Although the establishment of nonnative plants is recognized as a threat to native ecosystems, there are few documented examples of an invasive species directly influencing a rare native plant. The Eurasian biennial Dipsacus sylvestris (teasel) is invading the central New Mexico habitat of Cirsium vinaceum, an endemic thistle that is federally listed as threatened. We documented changes in teasel distribution and abundance between 1989 and 1993 that suggest the potential for direct interactions with the native thistle. We then compared habitat characteristics, germination behavior, and performance in greenhouse and field competition trials to evaluate the potential outcome of interference between these two species. There were no significant differences in measured habitat characteristics between sites supporting C. vinaceum and those with D. sylvestris. Dipsacus was better able to germinate in low light than the thistle, suggesting that D. sylvestris might invade C. vinaceum populations but that thistle recruitment would be unlikely in dense stands of the nonnative plants. In the greenhouse growth of C. vinaceum rosettes was significantly reduced by the presence of Dipsacus, but the invader was unaffected by the thistle; results of a short‐term field experiment were equivocal but suggestive of interference between the two. We suggest criteria for managers to use in determining whether invading species pose problems for specific rare native taxa, and we discuss the constraints on experimental work where protected taxa are involved.

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Cotton was central to Catalan industrialization and, within cotton, progress in spinning and weaving, originating in the late eighteenth century, provided the cutting edge in the industry's modernization. This article tests the current orthodoxy concerning the timing and causes of this breakthrough. It does so by first evaluating what were external influences on the success‐government policy, the elasticity of supply of spun yarn (a potential disincentive) and of raw cotton‐and then providing an analytical narrative of the advance first in hand and then mechanical spinning. On this basis a conclusion is reached that government policy was more advantageous to the development than posited in the current orthodoxy, that elasticity in the supply of spun yarn slowed the transition and that, though growing availability of American cotton eased the transition, the key to the development is to be found within the Catalan economy, experiencing a 'Smithian'‐type growth process in the eighteenth century, within which industrialization of cotton was nearly the last achievement before Spain's severe 'old régime crisis' curtailed economic opportunity.

The electronic spectra and 31P n.m.r. spectra of the complexes π-C5H5NiPPh3X (X = Cl, Br, I, NCO, NCS, NO2, CN, SnCl3, SnPh3, PbPh3, alkyl, and aryl) have been obtained and interpreted. The "common" anions form a spectrochemical series which is identical with that reported for many octahedral systems, while the carbon, tin, and lead donors lie relatively high in the series. Currently accepted theory for the chemical shifts of ligand donor atoms fails to satisfactorily rationalize the 31P chemical shifts.

The paramagnetic shift-reagent, tris-( 2,2,6,6tetramethylheptanedionato)europium( HI), was used to