Races which Have Arisen Suddenly in Nature. 97 
those which serve to separate genera amongst the Cru- 
ci ferae. 
The fruits of Capsella Heegeri are oval, and about 
as thick as they are broad. The seeds are notorrhizous. 
The valves lack the firm anatomical structure, character- 
istic of the normal valve, but are soft and full of sap, 
a condition which may be considered as due to arrested 
development. On the weaker branches in the autumn, 
deviations from this type occur which revert more or less 
to that of C. Bursa ; moreover the flowers and young 
fruits may develop into malformations, as the result of 
the attacks of Cystopus candidus, which closely resemble 
those of C. Bursa pastoris. 
The seeds of isolated plants of C. Heegeri gave rise 
solely to the parent type (382 examples) without rever- 
sion to C. Bursa. 
There can therefore be scarcely any doubt that C. 
Heegeri is a good elementary species which arose from 
C. Bursa in 1897, or a few years previously, somewhere 
near Landau. It is moreover a species which is dis- 
tinguished from its nearest allies by characters of far 
greater systematic importance than those which separate 
many species of known origin. 
I myself found a Stcllaria Holostea apetala not far 
from Wageningen in Holland under similar circum- 
stances (1889), and also in the same year the well-known 
Capsella Bursa Pastoris a petal a 1 near Horn in Lippe. 
But I did not succeed in obtaining seed from either of 
them. In 1888 I collected some seed of Lychnis I'csper- 
tiua not far from Hilversum and obtained some per- 
fectly glabrous plants by sowing it. The new variety 
L. v. glabra proved fully constant as soon as I was able 
1 See PENZIG, Tcratologic, I, p. 267. 
