Page:Proceedings of the Royal Society of London Vol 1.djvu/281

Rh Dr. Withering, on the contrary, remarked the connexion of the rings with fungi, but had not noticed their progressive enlargement.

During the growth of fungi, the author observes, they so entirely absorb all nutriment from the soil beneath, that the herbage is often for a while destroyed, and a appears bare of grass, surrounding the dark ring; but after the fungi have ceased to appear, the soil where they had grown becomes darker, and the grass soon vegetates again with peculiar vigour.

For the purpose of observing the progress of various circles, he marked them by incisions for three or four years in succession, and found their annual increase to vary from eight inches to as much as two feet, according to the species of fungus to which they are owing; for he has observed as many as ﬁve species that have this mode of growth ;—Agar2'cus campestris, Ag. arcades, Ag. pracerus, Ag. ter- reus, and the Lycqiertlnn havista.

The author has had many opportunities of remarking, that when two circles interfere with each other’s progress, they do not cross each other, but are invariably obliterated between the points of con- tact. The exhaustion occasioned by each obstructs the progress of the other, and both are starved; a circumstance which he considers as a strong conﬁrmation of his hypothesis.

He has further remarked, in one instance, that different species of fungi appear to require the same nutriment : for, in a case of inter- ference of a circle of mushrooms with another of puff-balls, the circles were, as in other cases, both obliterated between the points of union.

With the hope of ascertaining in what length of time a soil might recover the power of producing a fresh crop of fungi, a groove was cut along the diameter of a mushroom-ring, and a quantity of the spawn taken from its circumference was inserted along it: but the experiment unfortunately failed altogether, and the author had no opportunity of repeating the experiment.

The author’s observations on the stomachs of the porpoise and of ruminating animals, contained in two former communications, led him to believe that the fourth stomach of ruminating animals is sub-divided during life, in a greater or less degree, into two cavities. In the camel, and in some others, this division is permanent. In the bullock, sheep, 8w. it is only occasional. This arrangement leads to a presumption, that in the fourth stomach the food undergoes two changes, the one preparatory to the other.

With a view to investigate the subject, Mr. Home describes the internal structure of a series of stomachs, which he observes to form principal links in the gradation from the most perfectly ruminating to the truly carnivorous animals.