284 KARL- B. KRISTOFFERSON 



therelore more c<Mivenieiil to use the term oi Johannsen, \'\/.. isophene. 



The old method of naming the different isophenes with different 

 hdin names is troul)lesome even if only a rather small part of the va- 

 riation in V. tricolor should he treated. Clausen has made use of 

 another method. His denomination is a shortened description of the 

 morphological characters of the plants treated. Thus a plant with 

 violet flower (d = violaceus), large corolla ({/r ^ granchs I, well deve- 

 loped labellum (/«/? = lahellum), dark spot on the style (/uac^ma- 

 culatus) and closed pollen-magazine (c/ :^ clausus] is named v, gr, lab, 

 mac, cl. This method has its advantages. It becomes possible to 

 name an isophene by a simple counting up of the contracted latin 

 names of its characters, instead of beating one's brain with the inven- 

 tion of a multitude of latin names. Further, it would facilitate for the 

 biologist the understanding and the looks of a certain plant-associa- 

 tion, as well as the segregations for the geneticist. The reader of their 

 papers, on the contrary, will find this nomenclature rather trouble- 

 some. My line 2, for example, should be named (english contractions): 

 yel, sm, unhr, h-sm, h-cl, smlab, bwrd, l-gr, st-sm, hg, er-br, 

 er-max. The characters of the line were: light yellow corolla {yel), 

 small petals (sm), unbranched honey-streaks {iinbr}. small honey-guide 

 {h-sm), half closed pollen-magazine {h-cl), small labellum ismlcib), the 

 inlet to the stigmatic chamber directed backwards {bwrd), light-green 

 chlorophyll colour {l-gr), small stipules {st-sm), high stature {hg), 

 erect branches {er-br), erect main axis {er-max); not to mention other 

 characters. When a species is investigated to a very high degree (for 

 example as Drosophila) and the isophenes denominated in this manner 

 it would be necessary to add a dictionary to the paper for the reader's 

 service. 



The classifying of the isophenes of V. tricolor in systematical units 

 of higher orders might also be very difficult. The differences as to 

 the morphological characters are many in V. tricolor, and if free com- 

 bination occurs the number of isophenes will become very large. 

 Clausen has investigated 6 groups of characters, which gave 192 pos- 

 sible combinations. Perhaps some of these characters, being of »less 

 systematical value», may be left out; it is possible that other charac- 

 ters may be added, however. Such an elimination of characters less 

 valuable in systematics is possible, of course, although the question as 

 to the value of a character always becomes arbitrary. The inheritance 

 of most of the characters here treated — many of which must be used 

 in the systematizing of the subspecies or smaller groups — shows a 



