Mutations and Evolution. 
177 
Philadelphia, having larger flowers than in the previous case. (6) 
Meehan 1 records finding a double on the Wissanickon about 1854. 
(7) One near Beverly Bridge, Mass., 2 with panicle smaller than 
normal, the flowers full double, petals replacing both stamens and 
pistil. (8) Meehan 3 reported a double from North Woburn, Mass. 
These records, through trivial enough in themselves, acquire 
interest when considered as a whole. For they show that in a 
large part of its area and for over a quarter of a century 
S. Virginiensis was producing sporadic doubles as mutations. It 
is probably doing so still, and it may be that, as in stocks, some 
individuals are eversporting, giving rise to fresh doubles in each 
generation. 
Before leaving Saxifraga we may point out some of the other 
derivative forms which have been described in this genus. Sterns 4 
describes a form of S. Virginiensis on Manhattan Island which he 
called var. pentadecandra. In two plants observed nearly all the 
flowers had 15 stamens, the extra 5 replacing the petals. In these 
apetalous flowers the stamens were exposed in the bud. Such a 
change of petals to stamens is relatively rare. Several other 
plants in this location had apetalous flowers, but the stamens were 
ill-formed and more or less aborted. Three more specimens were 
found 5 in the locality in the following year. The same variation 
occurs in the cultivated European species S. granulata, as recorded 
by Masters. 
This must be regarded as a case of parallel mutations. In 
S. crassifolia an abnormal increase in the number of pistils has 
been repeatedly observed, while 5. Virginiensis var. chlorantha 
Oakes was described from Topsfield, Mass., 1847, having tiny 
green pubescent petals. 6 Var. pentadecandra was found in profusion 
in a slate rock locality in Essex Co., Mass. The Saxifrages are 
evidently subject in the wild condition to many mutations besides 
doubling. 
Thalictrurn anemonoides is another species for which there are 
a number of records of doubling. A semi-double found near 
Cincinnati, Ohio, in 1834 was taken into cultivation and in five years 
1 Amer. Nat. 2: 484, 1869. 
a Russell, J. L., Am. Nat. 3 : 327, 1869. 
Amer. Nat. 6: 487, 1872. 
4 Sterns, E. E. Some anomalous forms of Saxifraga Virginiensis. Bull, 
Torrey Bot. Club 14 : 122—125, 1887. 
* Bull. Torrey Bot. Club 15 : 166, 1888. 
6 See also Rhodora 19 : 143, 1917. 
