THE NATURE OF THE INFLORESCENCE AND 

 FRUIT OF PYRUS MALUS 



Caroline A. Black 



New Hampshire Agricultural Experiment Station 

 (with plates 33-40) 



The literature concerning the nature of the inflorescence and 

 fruit of Pyrus Malus is not in accord. The inflorescence is con- 

 sidered both determinate and indeterminate. The different parts 

 of the mature fruit have been variously identified and the fruit 

 is described under the inclusive term, pome, as originating in the 

 calyx, receptacle or stem, and accompanied by more or less carpel- 

 lary activity. The desirability of further study on this subject 

 being evident, the present work was undertaken by the writer. 



The material for this study was collected entirely from Baldwin 

 trees in an orchard used for experimental purposes by the New 

 Hampshire Agricultural Experiment Station, the collection cover- 

 ing a period of more than two years in order to furnish data for 

 more than one growing season. From March, 1913, to July, 1915, 

 collections were made at intervals varying from twice a week 

 when vegetation was most active to every two or three weeks 

 when the trees were dormant. The material was fixed in chrom- 

 acetic acid and in the chrom-osmic-acetic acid solution prepared 

 according to the formula of Mottier (1), washed, dehydrated, and 

 embedded in paraffin. It was necessary to remove the outer 

 scales and immerse the buds for a few seconds in a 50 per cent, 

 solution of alcohol to remove the film of air on the hairs on the 

 inner scales in order to secure penetration of the fixative. Sections 

 were cut from 17 to 25 /i and stained with Flemming's triple stain 

 or with Haidenhain's iron-alum haematoxylin. The triple stain 

 was preferable for detail of structure. 



The following morphological study on Pyrus Mains includes 

 the origin and development of the flower from the incipient shoot 

 and the subsequent formation of the fruit. The subject matter is 



519 



