Mr. J. Cleland on Vegetable Placentation, 



The structures of the Primroses seem also to support the 

 notion of a second carpellaiy whorl. In their case the common 

 marginal explanation appears to particular disadvantage, and I 

 hope to show that in respect to them too the free central expla- 

 nation is untenable. The ovules indeed are sessile, and so closely 

 set on the placenta, that it is impossible to say from their posi- 

 tion what is their arrangement — whether whorled round an axis 

 or in vertical rows. But other evidence is not wanting. 



Fig. 2. 



First, in a well-developed fruit of the Auricula, I have ob- 

 served a five-rayed star of cellular tissue in the centre (fig. 3). 



Secondly, at an early period the placenta of the Primrose is 

 formed of two parts, one in the centre vascular and united to 

 the torus, the other superficial, distinct, and easily removed, cel- 

 lular and bearing the ovules. If the ovules were buds, the cellular 

 tissue of their first origin could not have this superficial dispo- 

 sition, but would be the ascending axis of the plant, whose true 

 position is central. 



Thirdly, if the central part were a continuation of the axis, 

 we should find some at least of the fibrous bundles from the 

 stem running directly into it, but instead of that, the fibres are 

 entirely re-arranged at the base of the ovary ; a joint is formed 

 at this point by decreased size of the cells of the cellular tissue. 



