314 GENETICS IN RELATION TO AGRICULTURE 
smaller forms. That is, a dwarf form may spring from a large form or 
from another dwarf form as shown in Fig. 130. Another distinct group 
Fie. 130.—Bud mutations in sports of the Boston fern. At the right (b) is the form, 
magnifica, a dwarf, asexual descendant of the variety, bostoniensis. The fern in the center 
(a) is a sport from this dwarf. It has a tendency to produce further sports and so could not 
be depended upon to breed true. At cis shown a-small plant whose single frond resembles 
magnifica. At dis another sport that already displays instability in having two sorts of 
fronds. (After Boshnakian.) 
Fic. 131.—A series of pinne illustrating progressive variation in division. 1, Var. bos- 
toniensis; 2, Piersoni; 3, Whitmani; 4, Goodi (or gracillima); 5, Magnifica; 6, Craigi; 
7, Amerpohli. (Courtesy Brooklyn Botanic Garden.) 
contains the more delicate, open, lace-like forms, such as Mullsii and 
verona (Fig. 129b, d). The latter has an advantage over several earlier 
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