3l6 PHILOSOPHICAL TRANSACTIONS^ [aNNO 1706. 



sort of flesh. And having examined the spleen in 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 rooted, 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 in- 

 numerable 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 quan- 

 tities is contained in the veins, as may appear in great measure in those veins 

 which resemble arteries ; for the spleen can have no blood conveyed into it, 

 but what is brought to it from the heart by the arteries. 

 'They say that the spleen consists of a spongy flesh. I must own I could 

 not discover that ; for I allow of nothing to be flesh, but where the parts are 

 extended in length, and lye in a regular order by one another, and so compose 

 a muscle, and the ends of these flesh particles are joined in a membrane, or 

 make a tendon of a muscle ; whereas the parts of a spleen, setting aside the 

 fibrous parts, the arteries and veins, are composed of very small particles, which 

 are so exceedingly fine, that I can give no figure of them ; and it seemed to me, 

 that as the said fibrous parts spread themselves out into an unspeakable number 

 of very small branches, the said very small particles are depending on the 

 fibrous parts. 



In dissecting a flea, in order to take the heart out of the body, its sting ap- 

 peared much more plainly than I had ever seen it before ; and the more as I 

 had broken off the two fore-legs, which are as it were joined to the head, and 

 then placed the fore part of the flea before the microscope just as if it lay upon 

 its back ; by which means the sting of the flea appeared so distinctly, that I 

 could discover an orifice in the extremity of it, which appeared to have a cavity 

 throughout ; but what surprized me most was, that the sting had a scabbard 

 or sheath, in which the flea shut up his sting when he was not using it, and to 

 preserve it from harm ; and 1 imagine that the flea could so order the sting and 

 its case, as to place it between his legs, that it might not be entangled in the 

 hair or wool when he runs along. 



■'^•This scabbard of the flea is divided into two parts, each having a cavity like 

 a canal, in order to contain the sting when those parts are close shut together; 

 and it is very remarkable, that each of those hollow parts, that compose the 

 sheath or scabbard, is composed of parts resembling the teeth of a saw. These 

 teeth, I conclude, are so made as to indent within one another when the sting 

 is in the sheath, in order to hinder the opening of it, except when the flea would 



