1895.] on the Structure and Function of the Horse's Foot. 563 



ease. Does the foot in any way assist in its own circulation ? The 

 experiment which I am about to show you proves this very conclusively, 

 and demonstrates that a pumping mechanism exists, by which the 

 blood is forced out of the foot every time the weight comes on it. 



Into the veins of this foot I have placed two glass tubes, and both 

 are filled with water ; by projecting these tubes on the screen you will 

 be better able to observe that at the moment I press on the foot joint — 

 and thereby, as you will remember, depress the internal foot and at the 

 same time cause the whole part to slightly expand — the fluid rises 

 considerably in the manometer tubes ; when I remove the pressure the 

 fluid falls. Now in the living foot when the weight comes on the limb, 

 the blood is pumped with considerable force up the veins of the 

 leg, and at every movement this is repeated. That the living foot 

 behaves like our dead one, is proved by the fact that if a vein be 

 divided in the living animal, a jet, as if from a syringe, comes from it 

 every time the foot comes to the ground. 



The pumping action in the foot is due to the various movements 

 occurring in this organ, and without their aid it is probable that the 

 circulation in the foot would be carried on with extreme difficulty. 



Finally, let us briefly pass in review the changes occurring in the 

 foot from the time it makes contact with the ground until it leaves it. 



The weight is received on the posterior part of the foot and foot- 

 pad, by which means the plantar cushion resting above the foot-pad is 

 altered in shape ; the foot-pad and plantar cushion being com- 

 pressed and widened, each exerts pressure on the part of the foot 

 with which it is in contact, so that both the wall of the hoof and the 

 elastic cartilages are r>ressed outwards, and expansion of the foot occurs. 

 Concurrently with this the weight has been received on the 

 posterior part of the pedal joint with its yielding articulation formed 

 by the navicular bone. By the time the whole foot is flat on the 

 ground, the entire sensitive foot has become depressed within the 

 horny envelope, the heels of the hoof have sunk, and the coronary edge 

 travelled backwards. The body now passes over the foot, the limb 

 revolves as it were around one point, viz. the foot joint, and finally 

 the heels leave the ground, their width becomes decreased, while 

 the final propulsion to the body is given by the toe, which is the last 

 part of the foot to leave the ground. 



The hour allotted to this discourse has expired. I have had to 

 take you very hurriedly, and I fear very imperfectly, over a con- 

 siderable amount of ground, such, indeed, as might have occupied 

 our attention for several lectures, but I trust I have awakened an 

 interest in a very important subject, and that something may have 

 fallen from me which will be of use to you and to that animal to 

 which we are all so much attached. 



[F. S.] 



