162 TlMEHRI. 
of this the plants still shew themselves liable to destructive attacks it is 
more than ever necessary to enquire whether their constitution has not 
been deteriorated by long continued cultivation on the same spot 
without rotation. — I have &c, 
(Signed) Robert McLachlan. 
F. R. S., F. L. S. 
A Difficulty of Botanical Collectors. — There is a dif- 
ficulty which all who have collected herbarium specimens 
in but little explored lands must have felt and lamented. 
It is that it is almost impossible to get plants of certain, 
and among these some of the most interesting, genera 
examined and named. It is seldom that the collector 
himself has the time or knowledge, or if he has these that 
he has the opportunity — for instance that he has com- 
mand of the necessary books, to name his own plants. 
He therefore probably sends them to some such estab- 
lishment as that at Kew, to be examined and determined. 
But at Kew, as in more or less degree at similar estab- 
lishments, the scientific men employed, despite their 
ability and zeal, are unable to cope with the abundant 
material forwarded to them from all parts of the world ; 
and they therefore deal with certain plants, those belong- 
ing to genera in which any of the scientific workmen 
concerned feel some special interest ; but all the other 
plants are simply drafted, labelled with the name of their 
discoverer and the place and date of their discovery, but 
without any critical examination, into what appears to be 
their approximate place in the herbarium, there to lie 
until, perchance in a few cases, some new specialist 
interested in their particular genera may examine them. 
There are certain genera of plants which, in that they 
