the nervous system by the absorption of the poison into it, have been occasionally averted; but should symptoms of great depression be already present (as too frequently happens before the medical man arrives), he will endeavour, in that case, to rally the vital powers (scanty though the chances of success will then be) by small and repeated doses of sulphuric ether and ammonia combined, or should head symptoms require his interference, he must in that case bleed. CONDITIONS NECESSARY TO THEIR GROWTH. Of these, in fact, we know but little, and in the great majority of instances absolutely nothing; in a few cases moisture[97] and heat seem alone sufficient, even in our own hands, to cause some of them to grow; in others, electricity appears indispensable. A wet autumn is generally found to be exceedingly prolific in these plants, with the following notable difference as to _kind_: all those that are parasitical on trees show themselves, during a wet season, in amount directly varying with that of the previous rain, irrespective of any other influences conspiring to give this effect; whilst those, on the other hand, which issue from the earth, when the surface of this has been long chilled or when the electrical state of the air has not been materially modified for some time, will be found to come up sparingly or not at all, whatever rain may have fallen. An exception to this rule occurs in the common mushroom, which, by the combination of certain degrees of heat and moisture, may be reared throughout the year without the co-operation of electricity. A variety of plans have been recommended for this purpose, many of which are both troublesome and expensive; the following, taken by M. Roques from a scientific work on gardening, and said to be infallible, has, if so, the great advantage of extreme simplicity to recommend it:—“Having observed that all those dunghills which abounded chiefly in sheep- or cow-droppings, began shortly to turn mouldy on their surface and to bear mushrooms, I collected a quantity of this manure, which, so soon as it began to turn white, I strewed lightly over some melon-beds and some spring crops of vegetables, and obtained in either case, and as often as I repeated the experiment, a ready supply of excellent mushrooms, which came up from a month to six weeks after the dung had been so disposed of; but as an equable temperature is in all cases desirable to render the result certain, where this cannot be secured under the protection of glass, the next best plan is to scatter a portion of the above dungs mixed with a little earth in a cave or cellar, to which some tan is an excellent addition; for tan, though it kills other vegetable growths, has quite an opposite effect on funguses.”