484 PHILOSOPHICAL TRANSACTIONS. [aNNO 1720. 



coinmunicating with the small intestines, and discharging the alvine faeces, and 

 the lower orifice with the rectum, so that a clyster injected per anum is re- 

 turned by it. In the inner surface, now turned outwards, are seen a vast num- 

 ber of small glands, like warts, of a whitish grey colour, exhibiting a most curi- 

 ous appearance, and bleeding on being rubbed or touched roughly. The pro- 

 truded portion of the intestine is never wholly drawn into the abdomen ; a part 

 of it however retires when the stomach is empty ; on the contrary, when the 

 stomach is full, and especially when the person holds his breath, it is thrust out 

 to a greater extent. This person uses, without inconvenience, the coldest water, 

 and in winter-time even snow and ice mixed together, for cleansing the pro- 

 truded gut ; which moreover bears exposure to the coldest air ; except that it is 

 thereby contracted and hardened, and rendered of a somewhat paler colour. He 

 can eat all sorts of food ; but raw fruit and garden-stuff pass off undigested ; 

 and this is the case also with broths that are taken without solid food. 

 Wittemherg, Oct. 1, 1720. 



Observations on the Bones and the Periosteum. By Mr. Leuwenhoeck, F. R. S. 



N°366, p. 91. 



I have found, by frequent observations on the bones, that their superficial 

 part consisted of an inconceivable number of small vessels, and some few of a 

 larger size, which last, when they came to the surface of the bone, appeared 

 to be clothed with either a membrane, or a bony substance, that was perfectly 

 transparent. I once discovered, in a small portion of a shin-bone, 4 or 5 

 vessels of such a size, that a single filament of silk might have been drawn 

 through their aperture. One of these appeared to consist of 2 openings, each 

 seemingly provided with a valve, disposed in such a manner as to let out what 

 was contained in the vessel, but to suffer nothing to go in. 



As for that matter which issues out from the bone, and is carried into the 

 periosteum, I have discovered the source of it to be the spongy or cellular sub- 

 stance on the inside of the bone, which is the repository for the marrow. This 

 spongy substance consists of long particles closely united and linked together, 

 •which are composed of an infinite number of small vessels, some running 

 lengthwise, and others taking their course towards the sides of the bony parti- 

 cles ; which last, notwithstanding their great number of apertures, are yet ex 

 ceedingly hard ; some of them lying parallel, and others perpendicular to the 

 length of the bone 



Those particles, that lie perpendicular to the length of the bone, have vessels 

 proceeding from their extremities ; and from their sides, where they do not lie 

 close together, proceed other vessels, that compose the cortex, or superficial 



