No. 494] FASCIATWNS OF KNOWN CAUSATION 85 



for plant physiology at Amsterdam under the direction of 

 de Vries. That we are dealing with but a single branch, 

 and not several, though frequently the ribbed appearance 

 of a fasciation gives cause to think otherwise, is well 

 shown by Sorauer 24 in the case of a fasciation of the 

 Norway spruce, Picea excelsa. It is demonstrated first 

 of all by the position of the leaves, which are arranged 

 in continuous spirals, and further by the cross sections of 

 the fasciation at different points. They all show the 

 vascular bundles and the pith arranged as a single, con- 

 tinuous mass, and not as a combination of a number of 

 adjacent rings, which would have been the case had the 

 fasciation resulted through the union of various origi- 

 nally distinct branches. 



For the sake of convenience in discussion, the causes 

 of malformations in general and fasciation in particular 

 will be considered under four heads: (1) Mechanical ac- 

 tion, brought about by the elements, man or other verte- 

 brates; (2) cases where no injury can be traced; (3) the 

 action of fungi; and (4) the action of insects. 



Traumatisms appear, in the majority of cases, to be the 

 inciting causes of the appearance of teratological charac- 

 ters. Numerous instances of this are to be found through- 

 out our literature. Blarighem 25 found that in the case of 

 the pansy, Viola tricolor var. max ima, it was caused by an 

 accidental crushing of a young shoot. Similarly, he has 

 been able to constatate 28 that in clover fields which had 

 been mowed twice, the number of individuals of red clover, 

 Trifolinm pratense, bearing 4-5-foliate leaves, was from 

 12 to 37 per hundred, while in fields which never had been 

 cut, but 5 to 8 such plants were found per thousand. 

 Sainfoin, Onobn/chis saliva, under the same conditions, 

 produced in its pinnate leaf, leaflets grouped in threes 

 and fours. Plants of the ox-eye daisy, Leucanlhcmum 



24 Ibid., 333. 



28 Blarighem, L. Production par traumatisme d 'anomalies florales dont 

 eertaines sont hereditaires. Bull. Mus. d'Hist. Nat., 10: 399, 1904. 



28 Blarighem, L. Anomalies hereditaires provoqu§s par les traumatismes. 

 Compt. Bend. Acad. Sc., 140: 378, 1905. 



