Studies of Teratological Phenomena. 57 



involves a study of the conditions necessary to produce the character, 

 its transmission from generation to generation through seed, its vege- 

 tative propagation and the factors favorable to its minimum and optimum 

 development. 



1. Morpholo!S?ical. 



Fasciations, on the basis of changes which they bring about in 

 the external form of the stem, may be divided into linear (the ordinary 

 form), bifurcated, multi-radiate and ring categories. 



The first is the commonest type, the second has been observed by 

 de Vries to be a variation of the first, and often associated with it. 

 The third is also a variation of the first, in which the inflorescence or 

 affected structure separates at the apex into three or more short 

 branches. De Vries (M. T. 2: 497—8, 1910) figures this type for 

 Amaranthus speciosus. Quadri- radiate fasciations have been found by 

 the same investigator in Digitalis lutea and Celosia cristata, in the 

 case of the latter on a branched individual. Tri-radiate fasciated heads 

 are common in the Compositae. 



Ring fasciations are quite distinct morphologically from the other 

 forms and are not very common. Typical cases are found in the here- 

 ditary fasciated race of peas. Pisum sativum umhellatum and not un- 

 commonly in Veronica longifolia and Taraxacum officinale. In Veronica, 

 according to de Vries, they are less than a centimeter long, while in 

 Peperomia maculosa (M. T. 2, p. 496, 1910), they are sometimes a deci- 

 meter in length. Typical ring fasciation differs from the ordinary linear 

 form in that the main axis becomes distended into a funnel-shaped 

 structure, with the inner cavity somewhat freely exposed to the atmo- 

 sphere. De Vries calls these annular fasciations because the vegetative 

 cone is transformed into annular wall. I have observed a case or two 

 compara1)le to ring fasciations in Nicotiana. In Pisum, the character 

 is strictly hereditary, my statement being based on the observation of 

 over 300 plants grown in 1912. This type of fasciation appears to be 

 common in legumes, as it is also the form described by Bio d get t 

 (1905) for Pisum. De Vries is inclined to separate it from the ordinary 

 tj-pe because of its morphological and anatomical peculiarities, but Knox 

 (1908) says all the various forms are related to each other, the difference 

 being morphological, not physiological. Possibly the dissimilarities in 

 anatomical structure in some species and genera bring about the 

 distinctive character of the ring tj'pe, at least in those species where 



