18 BULLETIIsr 365, U. S. DEPARTMENT OF AGEICULTUEE. 



The present work includes the following 29 species of Del- 

 phinium: D. ajacis L., D, ande7'sonii Gray (National Herbarium 

 jSTo. 419245) , D. harheyi Huth, D. l)icolor Nutt., D. hlochmannm Greene 

 (National Herbarium No. 2060), D. calif ornicimh T. & G. (Na- 

 tional Herbarium No, 419726), D. cardinale Hook (National Her- 

 barium No. 1928), D. carolirdanum Walt. (National Herbarium No. 

 442717), D. consolida^ L., D. cwGuHatwm Aven Nelson, D. decorum 

 F. & M. (National Herbarium No. 1939), D. depamperatwn Nutt. 

 (National Herbarium No. 529204), D. geraniifolmnh Eydb. (Na- 

 tional Herbarium No. 245524) , D. geyeri Greene, D. glcmcum Wats., 

 D. rrhenziesii D. C. (National Herbarium No. 333235), D. nudicaule 

 T. & G. (National Herbarium No. 612398), D. occidentale Wats. 

 (National Herbarium No. 5,06615), D. recurvaturrh Greene, D. 

 robustwrrh Rydb., D. sapellonis CklL, D. scaposuni Greene, D. scopu- 

 loTUTTh Gray (National Herbarium No. 234530), D. siim/plex Dougl. 

 (National Herbarium No. 226416), D. tricorne Michx., D. trolliifo- 

 lium Gray, D. variegatum Gray (National Herbarium No. 342458), 

 D. vm'iegatuTrh apiculatwn Greene (National Herbarium No. 1887), 

 and D. virescens Nutt. 



These species were used, partly because tKey are the species which 

 have been met in the field work on poisonous plants, and partly be- 

 cause they were convenient to obtain for comparison. The specimens 

 of harheyi and Tnenziesii were from fresh specimens which were fixed 

 and embedded in the field, from specimens preserved in alcohol, and 

 from dried specimens. The sections of sapellonis and cucullatum 

 were from dried plants sent in from the field. The remaining speci- 

 mens were from the United States National Herbarium, the Economic 

 Herbarium of the Bureau of Plant Industry, and from the collection 

 of Mr. Ivar Tidestrom. In addition to these species of Delphinium, 

 stem sections were made of two species of Aconitum, for the purpose 

 of comparison, since the two genera are very similar in structure, and 

 since the two occur side by side in the field and both are suspected of 

 poisoning stock. 



In preparing the dried herbarium material for sectioning it was 

 treated with 2 per cent sodium hydroxid solution for 24 hours, or 

 until the tissues were softened and swollen, then washed thoroughly 

 in water, and put in a 10 per cent glycerin solution, the glj^cerin being 

 gradually concentrated through a period of several daj'^s. The sec- 

 tions were then cut in pith with a hand microtome, and stained with 

 safranin. Perfect sections are not always obtained by using this 

 method, but for the purpose of the identification of stems in field 

 work it is preferable in most cases to embedding. 



Comparison of the different species was based solely on the char- 

 acters appearing in the cross sections of stems. For each species 



