THE 



AMERICAN NATURALIST 



Vol. XLVIII April, 19 U No. 568 



THE ORIGIN OF x CAPSELLA BURSA-PASTORIS 

 • ARACHNOIDE A 

 DR. HENRI HUS 

 University of Michigan 

 Since Jordan 1 described a number of elementary spe- 

 cies of Capsella Bursa-pasioris, their constancy has been 

 a subject of cultural experiment. Herbarium material 

 demonstrates the existence of numerous apparently unde- 

 scribed forms. The finding of strikingly distinct forms, 

 such as Capsella Hcefjcri- and. more recently, C. Viguieri, 3 

 the work of Almquist 4 and that of Shull have added to 

 the interest which this species holds for the investigator. 

 It was Shull who determined the zygotic constitution of 

 various forms. To be able to demonstrate this with ex- 

 actitude is of the greatest value since Bateson and Lotsy 

 expressed their doubt astothehomozygocityof deVries's 

 Oenothera Lamarckiana. It was left to Nilsson 5 to clearly 

 show its necessarily heterozygous character. The inter- 

 est aroused by this paper leads me to believe that an 



