Systematic Atavisjn 639 



castrum, being limited to the base of the spike, 

 and decreasing in size from the lower flowers 

 upward. Connected with these atavistic bracts 

 is a feature of minor importance, which how- 

 ever, by its almost universal accompaniment of 

 the bracts, deserves our attention, as it is indica- 

 tive of another latent character. As a rule, the 

 bracts are grown together with their axillary 

 flower-stalk. This cohesion is not complete, nor 

 is it always developed in the same degree. 

 Sometimes it extends over a large part of the 

 two organs, leaving only their tips free, but on 

 other occasions it is limited to a small part of 

 the base. But it is very interesting that this 

 same cohesion is to be seen in the shepherd's 

 purse, in the wormseed and in the cabbage, as 

 well as in the case of the Erucastrum and most 

 of the other observed cases of atavistic bracts. 

 This fact suggests the idea of a common origin 

 for these anomalies, and would lead to the 

 hypothesis that the original ancestors of the 

 whole family, before losing the bracts, exhibited 

 this peculiar mode of cohesion. 



Bracts and analogous organs afford similar 

 cases of systematic atavism in quite a number 

 of other families. Aroids sometimes produce 

 long bracts from various places on their 

 spadix, as may be seen in the cultivated 

 greenhouse species, Atifhurium scherzerianum. 



