Of Hydatides Inclosed with a Stony Crust in the Kidny of a Sheep. By Mr W. Cowper, F. R. S.

IV. Of Hydatides inclosed with a Stony Crust in the Kidney of a Sheep. By Mr W. Cowper, F. R. S. In the Sheep's Kidney, which was ordered at a late Meeting of the Society, to be set aside for me to examine, I found a large whitish body, inclining to yellow, and ting'd with red, as it lay under the Membrane of the Kidney, vid. Tab. I. Fig. 1.A. This was very hard, as is usual in Animal Petrifications, 2 thirds of it lay hid within the substance of the Kidney: It was inclosed with a thick hard Membrane, that could not easily be separated from it, even with a Needle fixt in the end of a Stick. The Branches of the Emulgent Veins and Arteries, lay between it and the Pelvis of the Kidney; all which Vessels were somewhat press'd by this petrified Body. As I was picking off its thick strong Membranous Inclosures, I found the Needle slip into a cavity at an Aperture Fig. II. By this I was inform'd (of what I must confess, before I had no suspicion of) that this hard and heavy Petrified Body was hollow, whereupon I thought of dividing it with a Saw, but finding a Membranous Interstice in it, Fig 2. B. I pull'd it asunder, as express Fig. III. and found its inside divided by many Petrified Cells C. of irregular Figures, and fill'd with Hydatides, some of which are represented at D. This uncommon appearance (at least to me) of a Petrified Crust inclosing Hydatides, I thought deserv'd the Figures annext. Tab. I. Fig. I. The external Surface of the Kidney of a Sheep. A. The Petrified Body as it appear'd in it before dissection. Fig. II. The inferior Surface of the same Petrifyed Body, after the Membrane that inclosed it was taken off. a The Hole by which it was discover'd to be hollow. B. The Fissure by which it was divided, to shew its inside express. Fig. III. C. Its Petrifyed Cells that contained the Hydatides of various Sizes and Figures, express at D when taken out. V. Microscopical Observations on the Structure of the Spleen, and the Proboscis of Fleas. By Mr Anthony Van Leeuwenhoek, F. R. S. Delft, June 1. 1706. Amongst other things it has been observed, that the Spleen is compos'd of a spungy sort of Flesh: And having examined the Spleens of several Sheep, I found that the many Fibrous parts, of which it generally consists, and which many suppose to be Arteries and Veins, are in reality no Veins, but are united to, and draw their Nourishment from the Membranes in which they are radicated, and spread themselves into many Branches, and join with the Fibrous parts, which likewise appear with Roots and Branches growing out of the opposite Membrane, that I could not forbear viewing them with astonishment; imagining that all the innumerable fibrous parts were constituted to no other end, than to protrude the Blood which is conveyed into them by the Arteries; which Blood in great quantities is contain'd in the Veins, as may appear in great measure in those Veins