100 BOMBAY NATURAL HISTORY SOCIBTY. 
for every species there is a maximum and minimum of heat, which 
the plant will endure without harm, while an excess will kill the 
plant or at least prevent its distribution. It is a well-known fact 
that the faintest touch of frost is sure to destroy a Dahlia or a 
Heliotrope, while Chrysanthemums, Pansies and Datsies continue to 
flower even in several degrees of frost, also that many seeds of 
plants from colder climates, as of most Huropean weeds, do not even 
germinate in a tropical climate, and that many annuals only grow 
satisfactorily here in the cold season. On the other hand, most 
Indian plants, when cultivated in Europe, require a certain amount 
of artificial heat.. Some very interesting experiments and observa- 
tions have been made with the grape-vine, I believe, by a German 
botanist, who has succeeded in proving that this plant everywhere 
and under different natural conditions, requires the same total amount 
of degrees of heat for performing its growth and producing good 
fruit, and it may be regarded as certain that the same total amount 
of sunlight is necessary to produce the full chemical qualities of the 
grape, as colour, flavour, and sweetness. 
The limits of distribution for plants of the same species with regard 
to influence of temperature are sometimes very extensive. The rose, 
for instance, grows to perfection as far north as Sweden up to 60°, 
_N.L., though there certainly requiring protection in winter, and is at 
the same time satisfactorily cultivated here in Bombay. This fact 
may, however, partly be attributed to cultivation and to properties 
thereby acquired. But even among wild plants, several species with 
an equally large range of distribution, occur, as Solanum nigrum, 
which is a very troublesome weed all over Hurope, and not uncommon 
here in India, though perhaps originally introduced. Other plants 
have but a very limited range of distribution, as the Mangosteen, 
Garcinia mangostana, which is truly wild in the Malay Peninsula, 
but even in Bombay, not 20° farther North, isa very tender plant, 
though the same genus is represented by other species as Garcinia 
indica, the kokum, and Garcinia wanthochymus, which both yield 
pleasant acid fruits. 
A similar demonstration of these facts is pointed out in the Hon’ble 
Mr. Justice Birdwood’s excellent Catalogue of the Flora of Matheran 
and Mahableshwar, by comparing the vegetation of the ascents with 
that of the top of the hills, and which I need not further explain. 
By close observation of the plants of the same species or genus, 
wo shall find that they greatly vary even within the same range of 
