98 ALTERATION OF POSITION. 
very justly that no fair inference can be drawn from 
these facts as to the normal placentation of Cruciferee 
The same excellent observer has recorded the occur- 
rence of free central placentation in malformed flowers 
of Trifoliwm repens." 
In malformed flowers of Digitalis the change from 
axile to parietal placentation may often be seen. Mr. 
Berkeley describes an instance of this nature where the 
placentas were strictly parietal, and therefore receded 
from the distinctive characters of the order, and 
approximated to those of Gesneracee. 
The same author alludes to certain changes in the 
same flower where two open carpels ‘‘ were soldered 
together laterally, as was clear by the rudiments of 
two styles, the placenta being produced only at the two 
united edges, the outer margims remaining in the 
normal condition. ‘This may possibly tend to the ex- 
planation of some cases of anomalous placentation, for 
the only indication of the true nature of the placen- 
tation is afforded by the two rudimentary styles, im the 
absence of which the spongy receptacle of the seeds 
must have been supposed to spring from the medial 
nerve 
In other cases the placentas were parietal above, but 
axile at the base of the capsule, a striking instance of 
the facility with which axile placentation becomes 
parietal, the change being here effected by the pro- 
longation of the axis, and the formation on it of a 
second whorl of carpellary leaves. 
In double flowers of Primulacee similar alterations 
in the placentation may often be observed. I have 
seen in Primula sinensis sutural, parietal, axile, and 
free central placentation all on the same plant; nay, 
even in the same capsule the ovules may be attached 
in various ways, and transitions from one form of placen- 
tation to another are not infrequent. The late Pro- 
fessor E. Forbes describes” an instance of true foliar. 
! * Adansonia,’ iv, p. 70, t. 1. 
? Henfrey’s *‘ Bot. Gazette,’ 1, 265. 
