112 ERYTHEA. 



giving classificatory weight to these fruit characters, to be 

 sure that they have a reasonable constancy and are not clue 

 to teratogenic influences. Possible intergradations should 

 be sought and the material at hand shows that they are by no 

 means lacking. Especially the duhium type^ varies greatly 

 in different capsules, according as the change in the valves 

 and replum occurs near the summit (as in Fig. 13) or near 

 the base. In the latter case the capsule resembles and grad- 

 ually passes into the gracile type, in the former, the rhombic 

 type. So that the duhium type furnishes a very complete 

 series of transitions between them. But the variation does 

 not stop here, for further modifications furnish equally good 

 transitions to the fourth or capparideiim type. It will be 

 observed that the rhombic type scarcely differs from the caj^- 

 parideum type except in being 2-valved instead of 4-valved. 

 But capsules with three valves are by no means rare. The 

 third valve is sometimes very small and extends only a fourth 

 or half the length of the pod, one of the repla being split 

 only to that extent (Fig. 10, a), or sometimes the third valve, 

 while extending the full length of the pod, is narrower than 

 the other two, or finally the three valves are equal and regu- 

 lar (Fig. 18). In a similar way through the partial division 

 of the other column of the replum a more or less rudimen- 

 tary or incomplete fourth valve sometimes appears (Fig. 12, 

 e, shows the replum of such a pod), thus rendering the 

 transition from the 2-valved to the 4-valved type very com- 

 plete. 



Having thus described at some length the different forms 

 of capsules, we may proceed to their occurence. The gracile 

 type, as has been said, is the most common. It varies greatly 

 in size and pubescence, but less than any of the others in its 

 structure. The majority of plants, which have reached our 

 collections have fruit uniformly of this type, and there is 

 every reason to regard it as the normal fruit of the genus. 

 With the other types there seems to be much less stability of 

 form, and where any of them occur at all, it is not unusual to 



^So called because characteristic of T. duhium, Davidson, Erytlaea, ii, 

 179. 



