196 MR. MILLER CHRISTY ON 
also decreased by natural means. Ray, in 1660, recorded it * 
as growing “in Kingston and Madingley Woods, abundantly, and 
elsewhere [near Cambridge]" Though still abundant in the 
first-named wood, I can testify that it does not now occur in the 
latter, in which the Primrose grows. 
The Primrose, unlike the Oxlip, is certainly an aggressive and 
extending species. It readily extends to new plantations, hedge- 
rows, and railway embankments, as may be seen everywhere. 
May it not be, therefore, that the modest and retiring Oxlip 
is, in this country at least, being gradually hybridized out of 
existence by the more aggressive Primrose—that the Oxlip once 
extended over the whole of the extensive Boulder-clay district of 
Eastern England, but that its area has been, and is being 
gradually reduced by the Primrose advancing on all sides and 
even, to some extent, gaining access into its interior by means 
of the river-valleys—and that the half-vanquished Oxlip is now 
making a last, but obstinate, stand, entrenched (as it were) upon 
two of the highest, most impregnable, and most inaccessible 
portions of its once-extensive territory, its forces baving been 
cut in two by the onslaught of the potent Primrose, while two 
small companies are also able still to hold their own, though 
separated from the main body? This seems at least probable in 
view of what I have stated. 
I have sometimes been interested in observing the distance 
over which the hybridizing influence of one plant or the other 
may extend. The conclusion I have arrived at is that the two 
species are capable of producing hybrids one with the other when 
growing at a distance of from half-a-mile to a mile apart. 
may cite the case of Borley Wood, a very large wood in Cam- 
bridgeshire, in which Primroses are very abundant. Among 
them I found a fair number of plants which were obviously 
hybrids with the Oxlip; but, though I made a long search, | 
could see no trace of any pure Oxlip plants, though there may 
have been such. On entering Balsham Wood, another large 
wood lying from half to three-quarters of a mile further north, 
I found an abundance of Oxlips, together with a fair number of 
Primroses and hybrids between the two. Again, in à wood at 
Stanstead, in Suffolk, I found an obvious hybrid growing among 
Primroses when I had reason to believe that there were no Oxlips 
1660), 
* ‘Catalogus Plantarum circa Cantabrigiam nascentium’ (Cambr., 
P. 71. 
