Mutations and Evolution . 
179 
a strongly double red form. A double Anemone Pulsatilla is 
figured by Helwing as early as 1719. Doubling is well-known to be of 
frequent occurrence in the Ranunculaceae. A Convolvulus sepium 
with double flowers is described from New Brunswick, New Jersey. 1 
An interesting record is that of Sagittaria variabilis , 2 Engelm., 
a large patch of which, on an island in the Susquehanna, had 
completely double flowers. All the carpels of pistillate flowers and 
all the stamens of staminate flowers were converted into petals, 
giving the flowers the appearance of tiny snowballs. This 
probably represented a single individual mutation which had 
spread from rootstocks Elsewhere (Gates, 1917b) we have 
assembled numerous records of doubling in Trillium grandiflorum , 
the same root stock producing each year a double flower. There 
are various interesting records of double wild Rhododendrons. 
Rehder (1907) found in the woods at Glacier, British Columbia, a 
bush of B. albiflorum Hook, with double flowers. It was growing 
among normal bushes. In the double flowers, petalody of the 
stamens was combined with an increase in the number of staminal 
whorls. In the Alps, B, ferrugineum has been observed at least 
twice with double flowers, Kerner having found a large number of 
such shrubs in otle locality. Miyoshi (1910) has described the 
occurrence of doubles in B. bvachycarpum Don. The double form 
is called var. Nemotoi Makino. In the location (on a volcanic 
mountain) where it was found both white and rose varieties occur, 
but only the white showed doubling. Seven plants were observed 
with double flowers and ten with normal. In another place a 
group of five bushes was found, all with double white flowers. 
Nakai 3 found double and white varieties of B. Kaempferi in the 
vicinity of Karume, Japan. 
That cultivation does not produce doubling, even in a genus 
where doubles occur wild as mutations, is clear from the case of 
B. Metternichii , which is much cultivated in Japan but no double 
is known. If there is any relation between the environment and 
the occurrence of mutations in this genus, it remains elusive, as in 
most other organisms. We still have no better term than 
“ spontaneous ” to apply to it. 
Makino 4 cites also the finding of one double Oxalis corniculata , 
and Deutzia scabra entirely double in a locality in Nikko. 
1 Bull. Torrey Bot. Club, 17 ; 238, 1890. 
2 Porter, Thos. C., Bot. Gazette 1 ; 5, 1875. 
3 Bot. Mag. Tokyo, 29: 261, 1915. 
4 Journ. Coll. Sci. Tokyo, 1910. 
