THE PKI.MROSF. AND OXLIP IN KSSEX. 121 



agents ; l:)ut it should also be remembered that both plants have 

 enemies in birds. Sparrows, in particular, will feed on the ovules of 

 primroses as soon as they are developed and will destroy an 

 incredible nimiber of blooms. Still, after all these allowances, there 

 is a fL\ir proportion of seed ripened ; it is not, therefore, to the lack 

 of seed that paucity of plants can be traced. 



Taking into account the limited range of the IJardfield Oxlip in 

 Britain, it can hardly be regarded as an aggressive species. At one 

 place along the southern limit we have mentioned the area extends 

 as a tongue into the northern area of the primrose. This is at Box- 

 ted ^\'o()d, a little south of Great Saling. In the neighbourhood of 

 the wood the primrose grows very sparingly, but within the wood its 

 place is monopolised by the oxlips, and they can there be counted 

 literally by thousands. The explanation here is obvious that the 

 wood should be regarded as an outlier of the oxlip area which has 

 not succumbed to agricultural interference. 



The primrose cannot be regarded otherwise than as a diminish- 

 ing quantity in North-western Essex, which is partly due, as with the 

 Bardfield Oxlip, to agricultural and other influences, but more 

 particularly, as it would seem, to the want of agents for the dissemi- 

 nation of the seeds. This is the only rational explanation for the 

 narrow border to which we have adverted as being nearly destitute 

 of both species. Primroses are common enough south of that 

 border. 



\\'hy the primrose should be so exceedingly rare or absent in the 

 area inhabited by the oxlip, is not easy to say. Darwin says that its 

 range on the Continent '' differs somewhat from that of the cowslip 

 and primrose, and it inhabits some districts where neither of these 

 species live." Although, as we have observed, the presence of one 

 plant is not directly inimical to the other, there is doubtless some 

 indirect manner in which Primula elatior injures P. vulgaris. 



Darwin made many experiments on the cross-fertilisation of these 

 two species and of Primula veris, all nearly allied (see " Different 

 Forms of Flowers in Plants of the same Species "). Unfortunately 

 these experiments do not help us to a solution ; but incidentally 

 Darwin touches upon a proljlem which may be placed alongside of 

 our difficulty. In treating of the Common Oxlip, which is a hybrid 

 between P. veris and P. vulgaris, and is in nowise to be confounded 

 with the Bardfield Oxlip, he mentions the singularity of this hybrid 

 being freciuently found in some districts and rarely in others, and 



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