BOTA:acAr. subjects. 341 



envelopiug all in ti common slieatli, in the homogeneity of which 

 various degrees may he distinguished." 



From this it would appear that Van Tieghem considers the 

 puli)-carpels as tlie carpels, and that the parenchyma, whether it 

 envelops the whole carpel ball as in the Citrus, or each carpel 

 separately, as in the (Egle marmelos, as a something extraneous 

 to the carpels. Therefore, it would follow, as a logical conclusion, 

 that the covering of the parenchyma — the peel — must go with it, 

 and cannot, in Van Tieghem's view, be considered as the outer 

 surface of the pulp-carpels. 



Indeed, it would require only a little consideration to see that 

 the dorsal vascular bundle corresponds to the viidrib of the pulp- 

 carpel, and to the dorsal bundle of the pea-pod. If we took the 

 whorl carpels, which form the fruit of ih^ Aco}iite,ixm\ surrounded 

 it by a cellular jelly, we would have what Van Tieghem would 

 lead us to understand he means by the fruit of a Citrus, the jelly 

 corresponding to the parenchyma and external peel. 



From all this rather wearisome discussion it woidd appear 

 that although, ^Wwi a y«aV, Van Tieghem's study of the vascular 

 bundles of the Citrus pistil militates against my hypothesis, on 

 closer consideration it appears to support the idea that the pulp- 

 carpels form a whorl, independent of the enveloping peel. 



I would here remind the reader that my hypothesis is that the 

 peel is an atrophied whorl of carpels, which does not attract 

 towards its vascular ramifications, such as carpels with marginal 

 /er^iVi^ec/ ovules would do. It is possible, moreover, that too much 

 stress jnay be laid on the supposed signilicance of fibro-vascular 

 bundles, to identify an important from an unimportant organ. If 

 we throw our mind back to the genesis of things, we shall find 

 that Harvey describes seaweeds, which are fathoms long^ with 

 branches and sub-branches, and yet there is not a trace of fibro- 

 vascular bundles in their whole composition I All the biological 

 work is done by cell-to-cell indjil)ition, or l)y intercellular circula- 

 tion. It is only when we come to land ])lants, where resistance, 

 support, and circulating apparatus to pump up liquids from the 

 soil to every part of a tree, some hundreds of feet highj that a 

 complicated fibro-vascular system becomes necessary. Ihit in 

 atrophied parts it is obvious there is no neetl of vascularity. 

 They are wholly cellular. 



