Now, apart from what has been said, the following is sufficient proof that something is taken over from the veins10 into the arteries. If you will kill an animal by cutting through a number of its large arteries, you will find the veins becoming empty along with the arteries: now, this could never occur if there were not anastomoses between them. Similarly, also, in the heart itself, the thinnest portion of the blood is drawn from the right ventricle into the left, owing to there being perforations in the septum between them: these can be seen for a great part [of their length]; they are like a kind of fossae [pits] with wide mouths, and they get constantly narrower; it is not possible, however, actually to observe their extreme terminations, owing both to the smallness of these and to the fact that when the animal is dead all the parts are chilled and shrunken. Here, too, however, our argument, starting from the principle that nothing is done by Nature in vain, discovers these anastomoses between the ventricles of the heart; for it could not be at random12 and by chance that there occurred fossae ending thus in narrow terminations.
And secondly13 [the presence of these anastomoses has been assumed] from the fact that, of the two orifices in the right ventricle, the one conducting blood in and the other out, the former19 is much the larger. For, the fact that the insertion of the vena cava into the heart is larger than the vein11 which is inserted into the lungs suggests that not all the blood which the vena cava gives to the heart is driven away again from the heart to the lungs. Nor can it be said that any of the blood is expended14 in the nourishment of the actual body of the heart, since there is another vein20 which breaks up in it and which does not take its origin nor get its share of blood from the heart itself. And even if a certain amount is so expended, still the vein leading to the lungs is not to such a slight extent smaller than that inserted into the heart as to make it likely that the blood is used as nutriment for the heart: the disparity is much too great for such an explanation. It is, therefore, clear that something is taken over into the left ventricle.21
Moreover, of the two vessels15 connected with it, that which brings pneuma into it from the lungs is much smaller than the great outgrowing17 artery18 from which the arteries all over the body originate; this would suggest that it not merely gets pneuma from the lungs, but that it also gets blood from the right ventricle through the anastomoses mentioned.
Now it belongs to the treatise19 “On the Use of Parts” to show that it was best that some parts of the body should be nourished by pure, thin, and vaporous blood, and others by thick, turbid20 blood, and that in this matter also Nature has overlooked nothing. Thus it is not desirable that these matters should be further discussed. Having mentioned, however, that there are two kinds of attraction, certain bodies exerting attraction along wide channels during diastole (by virtue21 of the principle by which a vacuum becomes refilled) and others exerting it by virtue of their appropriateness of quality, we must next remark that the former bodies can attract even from a distance, while the latter can only do so from among things which are quite close to them; the very longest tube let down into water can easily draw up the liquid into the mouth, but if you withdraw iron to a distance from the lodestone or corn from the jar (an instance of this kind has in fact been already given) no further attraction can take place.
This you can observe most clearly in connection with garden conduits. For a certain amount of moisture is distributed from these into every part lying close at hand but it cannot reach those lying farther off: therefore one has to arrange the flow of water into all parts of the garden by cutting a number of small channels leading from the large one. The intervening spaces between these small channels are made of such a size as will, presumably, best allow them [the spaces] to satisfy their needs by drawing from the liquid which flows to them from every side. So also is it in the bodies of animals. Numerous conduits distributed through the various limbs bring them pure blood, much like the garden water-supply, and, further, the intervals22 between these conduits have been wonderfully arranged by Nature from the outset so that the intervening parts should be plentifully23 provided for when absorbing blood, and that they should never be deluged24 by a quantity of superfluous25 fluid running in at unsuitable times.
For the way in which they obtain nourishment is somewhat as follows. In the body22 which is continuous throughout, such as Erasistratus supposes his simple vessel16 to be, it is the superficial parts which are the first to make use of the nutriment with which they are brought into contact; then the parts coming next draw their share from these by virtue of their contiguity26; and again others from these; and this does not stop until the quality of the nutrient substance has been distributed among all parts of the corpuscle in question. And for such parts as need the humour which is destined27 to nourish them to be altered still further, Nature has provided a kind of storehouse, either in the form of a central cavity or else as separate caverns28, or something analogous29 to caverns. Thus the flesh of the viscera and of the muscles is nourished from the blood directly, this having undergone merely a slight alteration30; the bones, however, in order to be nourished, very great change, and what blood is to flesh marrow31 is to bone; in the case of the small bones, which do not possess central cavities, this marrow is distributed in their caverns, whereas in the larger bones which do contain central cavities the marrow is all concentrated in these.
For, as was pointed32 out in the first book, things having a similar substance can easily change into one another, whereas it is impossible for those which are very different to be assimilated to one another without intermediate stages. Such a one in respect to cartilage is the myxoid substance which surrounds it, and in respect to ligaments, membranes33, and nerves the viscous34 liquid dispersed35 inside them; for each of these consists of numerous fibres, which are homogeneous — in fact, actual sensible elements; and in the intervals between these fibres is dispersed the humour most suited for nutrition; this they drawn from the blood in the veins, choosing the most appropriate possible, and now they are assimilating it step by step and changing it into their own substance.
All these considerations, then, agree with one another, and bear sufficient witness to the truth of what has been already demonstrated; there is thus no need to prolong the discussion further. For, from what has been said, anyone can readily discover in what way all the particular [vital activities] come about. For instance, we could in this way ascertain36 why it is that in the case of many people who are partaking freely of wine, the fluid which they have drunk is rapidly absorbed through the body and almost the whole of it is passed by the kidneys within a very short time. For here, too, the rapidity with which the fluid is absorbed depends on appropriateness of quality, on the thinness of the fluid, on the width of the vessels and their mouths, and on the efficiency of the attractive faculty37. The parts situated38 near the alimentary39 canal, by virtue of their appropriateness of quality, draw in the imbibed40 food for their own purposes, then the parts next to them in their turn snatch it away, then those next again take it from these, until it reaches the vena cava, whence finally the kidneys attract that part of it which is proper to them. Thus it is in no way surprising that wine is taken up more rapidly than water, owing to its appropriateness of quality, and, further, that the white clear kind of wine is absorbed more rapidly owing to its thinness, while black turbid wine is checked on the way and retarded41 because of its thickness.
These facts, also, will afford abundant proof of what has already been said about the arteries; everywhere, in fact, such blood as is both specifically appropriate and at the same time thin in consistency42 answers more readily to their traction than does blood which is not so; this is why the arteries which, in their diastole, absorb vapour, pneuma, and thin blood attract either none at all or very little of the juices contained in the stomach and intestines43.
The End
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1
nutrient
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| adj.营养的，滋养的；n.营养物，营养品 | |
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accurately
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| adv.准确地，精确地 | |
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arteries
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| n.动脉( artery的名词复数 )；干线，要道 | |
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lighter
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| n.打火机，点火器；驳船；v.用驳船运送；light的比较级 | |
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traction
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| n.牵引；附着摩擦力 | |
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drawn
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| v.拖，拉，拔出；adj.憔悴的，紧张的 | |
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7
bellows
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| n.风箱；发出吼叫声，咆哮（尤指因痛苦）( bellow的名词复数 )；（愤怒地）说出（某事），大叫v.发出吼叫声，咆哮（尤指因痛苦）( bellow的第三人称单数 )；（愤怒地）说出（某事），大叫 | |
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8
nourishment
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| n.食物，营养品；营养情况 | |
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dilate
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| vt.使膨胀，使扩大 | |
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10
veins
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| n.纹理；矿脉( vein的名词复数 )；静脉；叶脉；纹理 | |
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11
vein
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| n.血管，静脉；叶脉，纹理；情绪；vt.使成脉络 | |
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12
random
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| adj.随机的；任意的；n.偶然的(或随便的)行动 | |
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13
secondly
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| adv.第二，其次 | |
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14
expended
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| v.花费( expend的过去式和过去分词 )；使用（钱等）做某事；用光；耗尽 | |
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15
vessels
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| n.血管( vessel的名词复数 )；船；容器；（具有特殊品质或接受特殊品质的）人 | |
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16
vessel
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| n.船舶；容器，器皿；管，导管，血管 | |
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outgrowing
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| 长[发展] 得超过（某物）的范围( outgrow的现在分词 )； 长[发展]得不能再要（某物）； 长得比…快； 生长速度超过 | |
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18
artery
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| n.干线，要道；动脉 | |
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19
treatise
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| n.专著；(专题)论文 | |
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20
turbid
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| adj.混浊的，泥水的，浓的 | |
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21
virtue
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| n.德行，美德；贞操；优点；功效，效力 | |
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22
intervals
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| n.[军事]间隔( interval的名词复数 )；间隔时间；[数学]区间；（戏剧、电影或音乐会的）幕间休息 | |
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23
plentifully
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| adv. 许多地，丰饶地 | |
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24
deluged
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| v.使淹没( deluge的过去式和过去分词 )；淹没；被洪水般涌来的事物所淹没；穷于应付 | |
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25
superfluous
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| adj.过多的，过剩的，多余的 | |
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26
contiguity
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| n.邻近，接壤 | |
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27
destined
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| adj.命中注定的；(for)以…为目的地的 | |
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28
caverns
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| 大山洞，大洞穴( cavern的名词复数 ) | |
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29
analogous
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| adj.相似的；类似的 | |
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30
alteration
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| n.变更，改变；蚀变 | |
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31
marrow
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| n.骨髓；精华；活力 | |
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32
pointed
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| adj.尖的，直截了当的 | |
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33
membranes
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| n.（动物或植物体内的）薄膜( membrane的名词复数 )；隔膜；（可起防水、防风等作用的）膜状物 | |
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34
viscous
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| adj.粘滞的，粘性的 | |
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35
dispersed
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| adj. 被驱散的, 被分散的, 散布的 | |
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36
ascertain
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| vt.发现，确定，查明，弄清 | |
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37
faculty
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| n.才能；学院，系；(学院或系的)全体教学人员 | |
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38
situated
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| adj.坐落在...的，处于某种境地的 | |
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39
alimentary
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| adj.饮食的，营养的 | |
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40
imbibed
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| v.吸收( imbibe的过去式和过去分词 )；喝；吸取；吸气 | |
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41
retarded
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| a.智力迟钝的，智力发育迟缓的 | |
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42
consistency
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| n.一贯性，前后一致，稳定性；(液体的)浓度 | |
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43
intestines
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| n.肠( intestine的名词复数 ) | |
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