638 Mutations 



stalks, but are limited to the lowermost part of 

 the raceme, adorning a few, often ten or twelve, 

 and rarely more flower-stalks. Moreover they 

 exhibit a feature which is indicative of the pres- 

 ence of an abnormality. They are not all of the 

 same size, but decrease in length from the base 

 of the raceme upward, and finally slowly dis- 

 appear. 



Besides these rare cases there are quite a 

 number of cruciferous species on record, which 

 have been observed to bear bracts. Penzig 

 in his valuable work on teratology gives a 

 list of 33 such genera, many of them repeat- 

 ing the anomaly in more than one species. 

 Ordinary cabbages are perhaps the best known 

 instance, and any unusual abundance of nour- 

 ishment, or anomalous cause of growth seems 

 to be liable to incite the development of bracts. 

 The hedge garlic or garlic mustard (AUiaria), 

 the shepherd's purse, the wormseed or Erysi- 

 mum cheiranthoides and many others afford 

 instances. In my cultures of Heeger's shep- 

 herd's purse, the new species derived at Lan- 

 dau in Germany from the common shepherd's 

 purse, the anomaly was observed to occur more 

 than once, showing that the mutation, which 

 changed the fruits, had not in the least affected 

 this subordinate anomalous peculiarity. In all 

 these eases the bracts behave as with the Eru- 



