April 6, 1883.] 



♦ KNOWLEDGE ♦ 



205 



body, and whose mission it is to carry the lymph to a tube 

 lying along the left side of the spine, and called the thoracic 

 duct. 



In the course of its passage from all parts of the boely to 

 the tlioracic duct, the lymph is made to pass through certain 

 organs, situated on the tracks of the lymphatic vessels. 

 These organs are called lymphatic glands. There is a :ol- 

 lection of these glands under the arm-pit ; another on each 

 side of the neck ; and another in tlie groin. The lymph, 

 after passing through these glands, appears to assume a 

 closer likeness to the blood itself, and of which, indeed, 

 lymph is really the fluid part. From all parts of our 

 bodies, then, these lymphatics are collecting the lluid part 

 of the blood wliich has e.xuded through the vessels in the 

 act of nourishing the tissues, and which is thus conveyed, 

 after elaboration in the " glands," to the thoracic duct. 

 Like the veins, the lymphatic vessels are provided with 

 valves, which prevent the flow of lymph other than in the 

 direction of the thoracic duct. 



yVe must now return to the chyle, or digested food, 

 which we left passing along the intestine. The chyle has 

 to be conveyed to the blood-current, as we have seen. Now 

 this function — that of ahaorj'tion — comniences by the chyle 

 passing through the delicate walls of the numerous little 

 processes called cilli, which stud the walls of the intestine. 

 There are millions of these villi on the lining membrane of 

 the intestine, each villus varying in length from half a line 

 to one-fourth of a line. Inside each villus one or two little 

 absorbent vessels (here called lurtmh) are found. The 

 chyle is taken up by these vessels, and thus passes out of 

 the digestive tube. Following up the chyle in its course, 

 we discover the absorbents which have received it, to pass 

 away from the intestine across the meacntery (or fold of the 

 lining membrane of the abdomen), and finally to end in 

 the thoracic duct at its lower portion. In their course 

 these absorbents, like those of the body, pass through 

 glands, which efFect some change in the constitution of the 

 chyle, and probably assimilate it more nearly in character 

 to the blood. 



It therefore follows that the thoracic duct must contain 

 a mixture of at least two fluids — chyh' from the digestive 

 system ; and lymjili, or the fluid part of the blood, gathered 

 from the body at large. We have ne.xt to inquire whither 

 these fluids are conveyed by this duct. The tlioracic duct 

 can be traced readily enough iu its course upwards and 

 along the spine. On the tight side of the body a smaller 

 duct exists ; but, for our present purpose, we may concern 

 ourselves simply with the principal duct, that of the left 

 side. Ascending in its course, we find that at the root of 

 the neck, on the left side, the thoracic duct opens into a 

 large vein (or at the junction of two veins) ; and we, there- 

 fore, arrive at the highly interesting fact that it is in this 

 region that fresh sujiplies of matter — chyle and lymph — 

 are poured into the blood. The latter fluid, renewed and 

 replenished, is thus adapted for its ceaseless work of 

 repairing the bodily waste ; and the chyle and lymph, 

 mingling with the blood, are swept onwards to the lungs, 

 and thence start, as part and parcel of the pure blood, on 

 the mission of liodily regeneration. 



In connection with the function of " absorption," which 

 we have just discussed, mention must be made of the 

 spleen. This organ is one of the "ductless glands," or 

 those possessing no outlet The thyroid gland in the 

 neck, and the pineal gland of the brain, are ranked, with 

 other glands, in this category. The spleen itself lies to 

 the left side of the stomach, and weighs from 5 oz. to 7 oz., 

 measuring in length about 5 in. or G in., and in breadth 

 3 in. to 4 in. Its colour is a bluish-purple, and is of soft, 

 pulpy texture. A large artery enters the spleen, and a 



large vein leaves the organ. Through the spleen, therefore, 

 a continual circulation of blood takes place. The spleen — 

 long a mystery to physiologists — is now regarded as a 

 lymphatic gland, devoted to the work of elaborating the 

 elements of the blood. We know that the blood which 

 leaves the spleen contains more minute globules than the 

 blood which enters the organ. Hence, wo conclude that 

 in the spleen-pulp these globules are manufactured. It is 

 also probable that the red blood globules are also altered 

 and transmogrified in the spleen ; which, thus, from the 

 fabulous function of generating the " evil humours " of the 

 body — witness, in proof of this, the still common expres- 

 sion, " a fit of the spleen," — has taken rank as an im- 

 portant blood-gland. The spleen, when enlarged, may be 

 removed from the body of man and animals, without any 

 apparent or serious disturbance of the health. In such a 

 case, it is probable that the other lymphatic glands perform 

 its work. 



TRICYCLES IN 1883. 



By John Browning, 



Chairman and Treasurer of the London Tricycle Club. 

 TWO-SPEED GEARINGS. 



JUST at tiie present time the great majointy of tricyclists 

 are devoting a deal of their attention to two-speed 

 gearings. Most of my readers will know that by this 

 term is meant some contrivance by which the tricycle can 

 be driven at a low rate of speed, but with a proportionate 

 gain in power up hill, and at a high rate of speed, with 

 a proportionate loss of power, down hill, the change from 

 one rate of speed to the other being made without stop 

 ping the machine. 



As most riders are anxious to obtain a machine fitted 

 with such a contrivance, or to have such an arrangement 

 adapted to a machine they possess, I think I cannot do 

 better than place before them the information I have 

 obtained on the subject ; much of which is the result of 

 actual experience. Although there are, as yet, actually 

 very few tricycles in existence with two-speed gearing, for 

 the last three years, I have, from time to time, had ma 

 chines of different kinds, both single and double (that is, 

 for one rider or two), geared up and down from as low as 

 '22 in., to as high as 50 in., and I have ridderj one single 

 machine belonging to my friend, Mr. Salmon, geared up 

 to 57 in. This experience has enabled me to form an 

 opinion as to the best proportion which should obtain 

 between the two gearings, and this is the most important 

 point in such a contrivance, and one which experience 

 only can determine. 



To simplify my remarks as much as possible, I must say 

 that by a gearing of 22 in. I mean that one revolution of 

 the crank would, with this particular arrangement, di'ive 

 the tricycle as far as if it had been fitted with a driving- 

 wheel or wheels 22 in. in diameter. Yet in some of the 

 machines with which I experimented, the driving-wheels 

 were as small as 30 in., while in others they were as large 

 as 48 in. 



I found then that 22 in. was too low for a double 

 tricycle for driving up a tolerably steep incline when only 

 one rider was working, and 50 in. was too high for me for 

 alight single machine; about 44 in. for such a machine 

 gave me a higher rate of speed with less exertion, though 

 of course to accomplish this I had to pedal much faster. 



But there is a great difference in this respect between 

 diti'erent persons. Some riders prefer a light machine 

 geared up to about 60 in., though this compels them to 



