261 



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 ring 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 ; Agaricus campestris, Ag. arcades, Ag. procerus, Ag. ter- 

 reus, and the Lycoperdon bovista, 



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. 



Observations on the Structure of the Stomachs of different Animals, 

 with a View to elucidate the Process of converting animal and vege- 

 table Substances into Chyle. By Everard Home, Esq. F.R.S. 

 Read April 30, 1807. [Phil. Trans. 1807, p. 139.] 



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, &c. 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. 



