FASCIATIONS OF KNOWN CAUSATION 



DR. HENRI HUS 

 Missouri Botanical Garden 



Among plants, whether in the garden or in the field, 

 individuals occur with greater or less frequency, which, 

 because they exhibit a striking departure from the accus- 

 tomed form, attract immediate attention. To denote such 

 abnormal forms, the term "teratological" is used. Tera- 

 tology covers a wide field. It includes the deviations 

 from the usual arrangement of the parts, such as the 

 union of organs and alterations of position, as well as 

 deviations from the form, number and size of the parts 

 of the plant. Frequently an explanation does not readily 

 offer itself, at other times the inciting cause is demon- 

 strated without trouble. 



Though it is only in comparatively recent years that the 

 true value of the study of abnormal forms has been real- 

 ized, it must not be thought that in the earlier days the 

 subject was overlooked. Numerous papers on terato- 

 logical cases were published during the seventeenth cen- 

 tury, for instance that by Wurffbain. 1 The eighteenth 

 century saw an increase in the number of similar publica- 

 tions. Even Linnaeus, before he enunciated his "varie- 

 ties levissimas non curat botanicus," seems to have de- 

 voted some time to the study of abnormal forms. 2 At the 

 same time, it was not until 1814 that the first collective 

 publication on this subject, covering more than 300 pages 

 and containing several illustrations, appeared. 3 This, at 

 greater or lesser intervals, was followed by others, the 



