appears in Araucaria brasiliensis, in which we have a condition almost exactly similar to what, I believe, exists in Dammara. If my supposition regarding Araucaria be correct, it cannot be imagined that Dammara, otherwise so nearly related, should differ so widely from Araucaria and the ordinary Abietineæ as it would necessarily do if the generally received opinion were correct. Thus, I conceive, that in Dammara we have, as in Araucaria brasiliensis, bracts with which the axillary scales (so to speak) are completely incorporated. On cutting the cone-scale of Dammara longitudinally, the female flower (" ovule") is seen to be supplied with a vascular bundle, which runs up from the base of the "scale," curving at its upper end to enter the inverted pistil. This vascular bundle is quite distinct from the mesial vascular bundle of the so-called scale, running parallel to it, and like it, in the mesial plane. This circumstance, although it does not of itself necessarily prove anything, yet tends to confirm the idea that the pistil of Dammara does not originate from the scale so called, but is only connate with it by its peduncle.

I feel satisfied that no one, who will without prejudice reflect upon the matters which I have just now been discussing, can fail to be convinced that the above is the only possible method by which the structures in Araucaria and Dammara can be reduced to a common type with our ordinary Coniferæ.*

There is one other question of interest in relation to the genera Araucaria and Dammara to which I may allude, although it is one which can only be determined with certainty by an appeal to their developmental history, viz., are their solitary pistils (so-called ovules) developed on tertiary axes, as in Abies, &c; or (what is probably the case) are they developed upon the extremity of the secondary axes-the "scales," or axillary shoots of the bracts? Upon this latter supposition we probably have in Cunninghamia a transition form between Abies, Pinus, &c., and Araucaria, with its allies. In Cunninghamia it is probable that, in addition to the two late

*It may be observed that the above reasoning is not necessarily depen lent upon any considerations as to the nature of the so-called ovules (pistils of Baillon), or of the squamæ fructiferx.

ral flowers of Abies, &c., a terminal flower is developed at the extremity of the axis of the scale. In Araucaria, &c., the two lateral flowers are not developed, leaving only the terminal one.

If there is any truth in this idea, it might be predicated, that of the three female flowers on the scale in Cunninghamia, the central one would be found to be developed first, the two lateral subsequently, a state of things resembling the centrifugal development of the female flowers in Cupressus, so clearly detailed by Dr Baillon.

The union of the bract with the axis of inflorescence in Cunninghamia, and with the peduncle in Araucaria and Dammara, is perfectly comparable to the connation of the axis of inflorescence with the leaf from whose axil it originates, in Tilia and Helwingia.

On the Acrid Fluid of the Toad (Bufo vulgaris). By JOHN DAVY, M.D., F.R.S. Lond. and Edin., &c.*

The fluid, the secretion of the cutaneous glandular structure of the toad, is a subject on which many different opinions have been entertained. The popular notion, handed down from a remote period, has always been that it is a poison. That notion some years ago was held to be a mere vulgar prejudice, and was pointed out as altogether an error, by so high an authority as Baron Cuvier.† In 1826 my attention was given to it, and the result of the inquiry was, that the fluid is simply acrid, an irritant, offensive as such, but not a poison. Subsequently, it was examined by two French physiologists, MM. Gratiolet and S. Cloez. The conclusion they arrived at was, that the secretion is a powerful poison, in some instances occasioning almost immediate death.§ Later still, Mr George Rainey engaged in the inquiry, and his re

* Read before the Royal Society of Edinburgh, 18th March 1861. Le Règne Animal,ˇii. p. 94.

Phil. Trans. for 1826.

§ A notice of these experiments is to be found in the "Spectator" newspaper of 28th August 1852.

sults, it would appear, are opposed to those of MM. Gratiolet and Cloez, agreeing perfectly with those I had before obtained.

Recently, viz. in August last, I made further trials of the fluid. The animals experimented on were a kitten, two days old, a fowl, and a slug (Limax ater). The toad, from which the fluid was collected was of ordinary size. It had been in confinement three days. The fluid was obtained by scraping the glandular surface secreting it with a knife. In each trial it was applied to a small wound in the cutis; and not merely applied by simple contact, but inserted and rubbed in. The animals were watched for twenty-four hours. The results were entirely negative. Neither the kitten, the fowl, nor the slug appeared to suffer in the least. The kitten did not refuse milk, although the part chosen for the experiment was the nose; nor had the fowl its appetite impaired ;-its head was the part selected for the trial.

These results agreeing with my former, and with those obtained by Mr Rainey, I shall not attempt to reconcile with those, so opposite, of the French physiologists.

I do not think that any material difference of quality of the fluid could have arisen from difference of climate or of season. My first experiments were made in the Ionian Islands; and the viscid fluid used-at the time copiously secreted—was acrid and irritant. The fluid last employed had the same bitter taste, and, applied to the tongue, excited the same kind of sensation as before experienced—an acrid one, but not severe, though of some hours' duration.

I have stated, in my early account of the fluid, that it was neither alkaline nor acid, it having had no effect in changing the colour of litmus or turmeric paper. MM. Gratiolet and Cloez say that they found it alkaline. The fluid which I have recently examined has also been neutral, similarly tested. They mention having kept it twelve months without its losing its activity. If kept in a damp place, might not its alkaline

* Quarterly Jour. of Micro. Science, No. 12, for July 1855.

During that time it had voided a good deal of excrement. The focal part consisted chiefly of the wings of insects; the liquid, the urinary part, contained a little urea.

reaction have been owing to a little ammonia developed? A small portion of the acrid matter collected from a toad in Barbadoes, in 1847, now, in 1860, shows a decided acid reaction. It was melted, when collected, at a low temperature, just sufficient for its fusion, after being dried. It has been kept since in a dry place, and it seems unaltered in its properties. It is bitter, and, judging from its effect when applied to the lip, it is even more acrid than the fresh fluid of our English toad. Moreover, mixed with water, its character under the microscope is similar-minutely granular; and I have not found it different in its effect. When applied to a fowl in the manner before described, the result was equally negative.

The toad of Barbadoes, it may be mentioned, if not identical in species, has a great resemblance to our toad. It differs chiefly in being of a lighter colour, of a somewhat more slender make, and more active in its habits. Incidentally I may remark, that though introduced from Dominica only a few years ago, it has now spread all over the island; also, that it is considered poisonous there by the natives. It is said that dogs that had eaten it became mad. Perhaps the acrid fluid made them wild, and their disturbed state was called madness. It is also asserted, that now the dogs have gained experience of its effects, they leave the toads unmolested, carefully avoiding them. For the accuracy of these reports, of course I cannot vouch. It would be an interesting circumstance, were it sufficiently well authenticated, that the experience of one dog, or generation of dogs, had been transmitted, and the acquired aversion become hereditary, as is known to be the case with some of the habits of brute animals.

I have stated that the microscopical character of the acrid matter of the toad of Barbadoes is similar to that of the toad of this country. Both consist of a fluid in which are suspended an infinity of granules of an extremely minute size, so much so as not to be discernible under a quarter of an inch object-glass, and yet, when seen with the one-eighth inch glass, though excessively small, they are well defined. In one instance I estimated their diameter to be about booth of an inch.

*The fluid mentioned above was from a male in the month of April, in the

In relation to the use of the acrid fluid, I have before expressed the opinion, that as it is so offensive to the taste, and irritating, it is well adapted to secure the sluggish and otherwise defenceless animal from being devoured. I may mention, in confirmation of this view, that the secretion seems to be in some measure under the will of the animal. When I have seized one of its limbs with a forceps, or pinched its skin, the acrid matter has been immediately poured out, and not only in the exact spot where the pressure was made, but also from the adjoining surface, and so conspicuously that there could be no doubt about it.

If so protected, a question may arise, how is it that this animal is not more abundant? One reason may be, that the very young toad, after its final metamorphosis from the tadpole state, is, I believe, in a manner defenceless. The expression of belief is used, the conclusion being founded on the examination of a single specimen, and consequently requiring confirmation. Another circumstance may be, the little power possessed by the toad of resisting cold. I have found a temperature two or three degrees below the freezing point fatal to it; for instance, when it has been exposed, unprotected by any covering, to the open air for a few hours during a frosty night towards the end of autumn. Now, as the toad in the early winter, or shortly before its setting in, seeks its hybernating abode, and there becomes torpid, should the season be unusually severe, not having the power of quitting its selected. spot, it may be frozen and die. The rapid manner in which the toad has multiplied and spread in Barbadoes, and the greater abundance of, and the larger size attained by this animal in a southern climate, such as that of the Ionian Islands, seem favourable to this conclusion.

neighbourhood of Edinburgh, caught when on the back of a female in coitu. It may be worthy of remark, if a single observation may be trusted, that the larger female differs from the smaller male in having her skin apparently destitute of the acrid secretion, at least during the breeding season. In the male, at the same time, it was unusually abundant. The latter, at this season, perhaps, may afford sufficient protection to the former, whilst the ova are passing from the oviduct; and in her, the growth of the ova" may determine from the skin, for a time, and render the glandular structure inactive.