UNION OF DIFFERENT SPECIES OF PLANTS. 
251 
until the plant again shows signs of growth. In this way, the 
health of the Acacias and most other New Holland shrubs may 
be kept up ; for if they get the proper seasonal treatment they 
are very hardy. If the phyllodia become discoloured, or shrivel, 
or drop off, it generally arises from disturbing the plant with the 
stimulus of water at the season when it ought to be left in perfect 
repose. 
In a window of a common apartment, or in a greenhouse, where 
the plants of many climates are collected together, it is not easy 
to get a sufficiently dry atmosphere for New Holland shrubs ; and 
therefore, to grow them in high perfection, they should have a 
house for themselves. When mixed with other plants, some of 
them requiring a moist atmosphere, the New Holland shrubs will 
never succeed to absolute perfection ; and the best chance that 
they have is to keep them as dry as possible during the season of 
repose. 
UNION OF DIFFERENT SPECIES OR VARIETIES OF 
PLANTS. 
That such unions are practicable has been long known among 
cultivators. The art of budding and grafting is an every-day 
expedient; but this is a connexion rather than a union : the 
parts are never interblended: each remain as distinct as they 
were before they were united. The fluids absorbed by the roots 
nourish and support both ; but there is no intermixture of their 
respective membranes, only a simple attachment of the cellular 
matter acting like cement. The wood of the stock and that of 
the graft, however exactly fitted in the operation, cannot possibly 
unite : it is the cellular tissues of the bark, and increasing 
alburnum, that forms the junction. 
Some propagators have supposed that if the shoots of two 
different species of the same genus were so closely united length¬ 
wise, by removing the opposing sides, and binding the wounded 
surfaces together, as to form one entire shoot, that there could 
not but be some interchange of their respective qualities or pro¬ 
perties ; and that flowers or fruit of a mixed character would be 
the result. Shoots have been so tried ; bulbs and tubers have 
