156 ALTEILVTION OF POSITION. 



position. In the latter case, as often happens in the 

 seeds of the orange, the new products are placed by 

 the side one of another.^ 



For other cases of prolification or the adventitious 

 formation of buds on leaves, roots, &c., see under 

 Heterotaxy. 



CHAPTER III. 



HETEROTAXY. 



Under this category are here included a variety of 

 deviations from the ordinary arrangement and position 

 of parts which cannot conveniently be classed under 

 the preceding or under other headings. The term 

 heterotaxy is intended to apply to the production 

 of organs in situations where, under usual circum- 

 stances, they would not be formed. It thus does not 

 include cases of substitution, where one part is re- 

 placed by another, or more or less metamorphosed, 

 nor cases of multiplication, nor of prolification which are 

 characterised not only by the production of members in 

 unwonted situations, but also in unwonted numbers. 

 From the very nature of the anomalies, and specially 

 from the scanty knowledge we possess concerning their 

 mode of development, it is not possible to allocate them 

 in all cases correctly, and moreover many of them 

 might as well be placed in one group as in another. 



Formation of adventitious roots. This is of exceedingly 

 common occurrence in a vast number of plants, so 

 much so that in most cases it cannot be considered 

 as in any way abnormal ; there are, however, a few 

 instances where* the formation of these organs may be 



> El. Ter. Veg.,' p. 364, Adnot. 



