Griggs : Characters of the Plataxaceae 393 



supposition of a deciduous perianth and of modifications due to 

 pressure, factors which though potent in many cases cannot be 

 invoked to explain the flowers o{ PI at anus. 



Moreover, because of the hairiness and the early h'gnification of 

 the inflorescence the sycamore is an exceedingly difficult object to 

 handle even by the best methods of modern technique, which had 

 not been invented at the time of Schoenland's work. He himself 

 recognized very clearly the insufficiency of his methods, concern- 

 ing which he says (p. 313): ''A complete isolation of the individual 

 young flowers is possible and was accompHshed by me in different 

 ways; but the advantages obtained thereby are very doubtful, 

 since, because of the density of the inflorescence, parts of the prep- 

 arations are easily torn off, which naturally introduces numerous 

 errors. 



" I have preferred therefore for the most part to cut thin sec- 

 tions from heads hardened in alcohol, and to observe them in 

 glycerine by reflected and transmitted light. The thick pubescence 

 of the bud-scales and of the sepals is extremely disturbing, so that for 

 the most part one can determine in this way nothing certain regard- 

 ing the sepals or the petals which they cover, especially since there 

 occur, irregularly distributed between the individual flowers, rather 

 long hairs which are entirely distinct from the pappus-like hairs of 

 the fruit. In the staminate or apparently perfect flowers this 

 method is of no service, since here the thick pubescence of the 

 anthers or staminodes makes, every observation impossible. In 

 these I was limited to longitudinal sections of the flowers, and 

 although I am aware that one can use results which are obtained 

 in such a way only very cautiously, on account of the impossibility 

 of orienting the sections satisfactorily, yet I believe that I have 

 reached correct conclusions from them, since they are in perfect 

 accord with the facts otherwise determined." We must admire the 

 perseverance of a man who w^as w^illing to attempt scientific work 

 under such difficulties but we cannot give much weight to his 



results. 



It is apparently safe to assume that the Inflorescence of Pla- 

 taniis has attained its present very compact condition by the 

 shortening of the pedicels of the individual flowers. To what 

 extent this shortening has involved loss of floral parts is a matter 



