BIOTYPES AND HYBRIDS. 31 



such case there were sibs having- the same external characteristics, which 

 behaved in an altog^ether different way when bred. Thus, a sib (057.25) 

 of the attenuate-lobed specimen (057.20) noted above as producing- off- 

 spring- uniformly of the parental type, was, like that plant, attenuate-lobed, 

 but its offspring-, instead of agreeing with the parent, consisted of 1 plant 

 entirely without lobation, 168 with obtuse lobes, 186 with some of the lobes 

 slightly elong-ated, and 415 with attenuate lobes. This result looks very 

 much like a case of Mendelian inheritance if we assume that the parent 

 was a DR, but it is not at all in accord with such an assumption that in 

 like inanner obtuse-lobed sibs of the plants whose entire progenies were 

 characteristically obtuse-lobed as described above have produced offspring- 

 ranging- from the totally unlobed condition to the well-marked attenuate- 

 lobed extreme. For example, one of these obtuse-lobed plants (052.182) 

 whose seeds were sown February 12, 1906, produced a family of 471, of 

 which 337 were observed to have the following composition : 11 were wholly 

 unlobed, 43 were unlobed in the distal half of the leaf, but had small trian- 

 gular lobes in the proximal half, 89 were obtuse-lobed throughout, 102 had 

 some lobes slig-htly elong-ated, and 192 had some lobes strongly attenuate. 



Besides a few families that were left crowded too long- in the seed-pans 

 to allow of a satisfactory estimation of the foliar characteristics, 15 addi- 

 tional families were reared from parents which had attenuate lobes and all 

 g-ave uniformly the same result, namely, progenies showing the complete 

 rang-e of variation from a wholly unlobed condition to the attenuate condi- 

 tion of the parent; 17 families from obtuse-lobed parents had the same 

 composition, as did also 7 families from unlobed parents. 



Besides these variations, which can be easily arranged in a simple linear 

 series, there were noted several variations of so definite a character as to 

 lead to the attempt to seg-reg-ate them as distinct forms. Thus one form 

 which appeared in several families {e. g., 0527, 05182, etc.) was charac- 

 terized by a distal unlobed half of the leaf and a proximal half with tri- 

 angular lobes. Another g-roup of specimens (0623) of strikingly uniform 

 appearance had very robust rosettes with leaves broad, obtuse, and entirely 

 unlobed except for the presence, occasionally, of a few shallow triangailar 

 lobes at the very base. 



If further breeding should confirm the conclusion that these families 

 belong to a single biotype, including within its normal rang-e of fluctuation 

 individuals with obtuse lobes or no lobes at all and others with strongly 

 marked attenuate lobes, this form would be indistingaiishable in some of 

 its phases from B. bp. simplex, and in other phases it would closely re- 

 semble B. bp. tenuis. Only breeding-tests could safely distinguish these 

 several types, and so long- as the practical taxonomist's work consists en- 

 tirely in the classification of individuals as they occur in nature, he would 

 be justified no doubt in refusing- to recognize such elementary species as 



