ON THE DISTRIBUTION OF ABNORMALITIES IN THE 
INFLORESCENCE OF SPIRAEA VANHOUTTEI 
J. Arthur Harris 
I. Introductory Remarks 
Experimental breeders, primarily de Vries, have shown that in 
certain races individuals of more or less mutually exclusive charac- 
teristics may regularly occur in fairly constant proportions. Students 
of hybridization have devoted their chief effort for the past fifteen 
years to a study of the laws of segregation of parental characters in 
filial generations. Those interested in experimental morphology 
recognize the fact that a pure bred individual may in the course of 
its ontogeny display characteristics which might belong to distinct 
varieties or species. 
In its relation to both genetic and morphogenetic problems the 
investigation of the distribution of abnormalities among the syn- 
chronously developed organs of the same individual seems of im- 
portance. 
The purpose of the present note is to call attention to peculiarities 
of the frequency disrtibutions of certain abnormalities of the pedicels 
in one of the most splendid garden spiraeas, S. Vanhouttei. 
II. History of Spiraea Vanhouttei and Discussion of 
Morphology of Inflorescence 
I. History of S. Vanhouttei (Briot) Zbl. 
Briot writes of the origin of the form which he refers to as Spiraea 
agiiilegifolia vanhouttei^ "Cette variete, obtenue par M. Billard . . . 
de graines du Spiraea aquilegifolia.'' He also states: "Le Spiraea 
aquilegifolia est, dit-on, une forme du Spiraea trilohata.'' In his 
original description ZabeP gives no statement as to where or when 
this "hybrid" was formed. In a later paper^ he merely refers to it 
1 Briot, Rev. Hort. 37: 269. 1866. 
2Zabel, H., Gart. Zeit. 3: 496. 1884. 
sZabel, H., Mitteil. Deutsch. Dend. Ges, 1904: 59. 
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