BIOTYPES AND HYBRIDS. 23 



more characteristic specimens of B. dp. rhomboidea secured in hybrid fam- 

 ilies. These two individuals were growing- in a situation which received 

 only the morning' sun. The leaves were divided to the midrib, but the 

 oblong 1 , obtuse lateral lobes frequently had no incisions, thoug"h in some 

 cases the middle lobes of the leaves had the more characteristic incision on 

 the distal margin and less frequently a similar incision occurred on the 

 proximal margin . The lobes were rather distant from each other, giving 

 a very unique appearance to these plants. Seeds of these two supposed 

 sibs were sown on June 6 and 14, 1905. The first of these (040.1) pro- 

 duced 65 offspring, which were studied in their relation to different condi- 

 tions of environment in order 

 to get a clue to the suscepti- 

 bility of Bursa to immediate 

 modification by variations in 

 the chemical and physical con- 

 ditions of the soil, differences 

 in soil-moisture, atmospheric ( 

 humidity, intensity of light, 

 etc. 



Specimens which were grown 

 under as favorable conditions 

 as the sky-lighted room pro- 

 vided were essentially identi- 

 cal with the parent (fig. 12). 

 Aside from the complete sup- 

 pression of lobes and long 

 delay of the flowering period 

 in dim light (figs. 13 and 14), FIG. 14. Bursa bursa-pastoris rhomboidea. A sib 

 the most marked effect of en- of P lants shown in fi s - V1 and 13 > and of the same 



vironment was noted in plants ^ sh . ow ; ng the com P lete , su PP ression of lob ^ 

 . I his plant was grown for five months in a poorly 



kept in a nearly saturated illuminated corner of the sky-lighted room, 

 atmosphere attained by cov- 

 ering with glass jars. The leaves became long, of very thin membranous 

 texture, crinkled and othenvise distorted, and with very shallow sinuses 

 (fig. 15) . Plants which had been grown in the dim light of the sky-lighted 

 room of the laboratory and which showed a consequent reduction of the 

 lobes returned to the fully lobed condition upon being removed to the better- 

 lighted propagating-house. Seeds of one of these (051.19) were sown 

 March 6, 1906, and produced a large progeny, only 100 of which were potted 

 up and studied. These were uniform throughout, but as they were stunted 

 by unfavorable conditions in the propagating-house it was impossible to 

 determine with certainty their relation to other cultures which had been 

 grown under better conditions. 



