闻之直行曰经。横行曰络。诸脉之浮而外见者。皆络脉也。络也者。本经别出之旁支。联系于他经者也。析
而论之。经十二。络十五。皆辨其行。以分其部。按其部。以诊其病焉。经络论。黄帝问于岐伯曰。夫络脉之见
也。其五色各异。青黄赤白黑不同。其故何也。岐伯对曰。经有常色。而络无常变也。言经脉之色有常。络脉
之色无常也。帝曰。经之常色何如。岐伯曰。心赤、肺白、肝青、脾黄、肾黑。亦皆应其经脉之色也。言五脏之经。
应五脏之色也。帝曰。络之阴阳。亦应其经乎。岐伯曰。阴络之色应其经。阳络之色变无常。随四时而行也。
言阴络之色应五脏。阳络之色应四时。阳外而阴内也。其寒多则凝泣。凝泣则青黑。热多则淖泽。淖泽则
黄赤。此皆常色。谓之无病者。以其变之因乎时。不因乎病。故亦以为常也。五色具见者。谓之寒热。以其不
应时之寒。不应时之热。故以为寒热也。皮部论曰。其色多青则痛。多黑则痹。黄赤则热。白则寒。五色皆见。
则寒热也。盖阳络随时而行者。变从乎外。天道之常也。因病而见者。变从乎内。人道之变也。合时与病而
察之。可知其变中之常。常中之变矣。至于两跗上脉竖坚陷者。足阳明病。鱼络血者。手阳明病。手鱼络青
者。胃中有寒。鱼际络赤者。胃中有热。鱼际脉黑者。或者痫候。其暴黑者。留久痹也。其青短者。少气也。颈脉
动。喘疾咳曰水。耳间青脉起者。为掣痛。耳后完骨上青络盛。卧不静者。是痫候。臂多惕脉者。谓之脱血。经
脉动惕者。久而成痿。惊跳不定者。即为脉虚。青紫之脉。散见于面者。多病风热。红赤之脉。散见于腮者。多
病痘疹。此皆阴阳之络。因病而变者。亦宜合时与病而察之也。然愚谓营行脉中。卫行脉外。络脉之见。皆
当有血色以间乎其中焉。变见于左者。应在左。变见于右者。应在右。左右皆见。左右皆病。察其何部何色。
而断其何脏何腑也。至于络之形容。亦有粗细浮沉长短缓急之殊焉。推而论之。则络之粗者。病气有余。
络之细者。形气不足。犹脉之大则病进。细则气衰也。络之浮者病在外。络之沉者病在内。犹脉之浮为在
表。沉为在里也。络之长者气治。络之短者气病。犹脉之长则气治。短则气病也。络之紧急者为寒。络之纵
缓者为热。犹脉之急为寒。缓为热也。于是乎因人大小。而定络之粗细。因人肥瘦。而定络之浮沉。相时寒
暑。以验缓急。相时冷暖。以验短长。八法互观。合之络色。参之脉证。庶乎可通其变矣。经曰。凡此十五络者。
实则必见。虚则必下。其见浮而坚。其见大而明者多血。细而沉者少气。亦此意欤。若夫幼科食指之纹。即
手太阴之络也。痘科耳后之筋。即手少阳之络也。皆可以是参观者也。
It is heard that those running straight are called Jing (Meridians), and those running horizontally are called Luo (Collaterals). All vessels that float and appear on the surface are Luo Collaterals. The so-called Luo Collaterals are branches diverging from the main Meridian, connecting with other Meridians.
Analyzing them separately, there are twelve Jing Meridians and fifteen Luo Collaterals. One must distinguish their courses to divide their regions; by palpating these regions, one can diagnose diseases.
In the *Luo Mai Lun* (Treatise on Collaterals), the Yellow Emperor asked Qibo: "When Luo Collaterals appear, their colors vary among the five hues—green, yellow, red, white, and black. What is the reason for this?" Qibo replied: "Jing Meridians have constant colors, whereas Luo Collaterals do not have fixed variations." This means the color of the Jing Meridian is constant, while the color of the Luo Collateral is variable.
The Yellow Emperor asked: "What are the constant colors of the Jing Meridians?" Qibo said: "The heart is red, the lung is white, the liver is green, the spleen is yellow, and the kidney is black. These also correspond to the colors of their respective Meridians." This indicates that the Meridians of the Zang Organs correspond to the colors of the Zang Organs.
The Yellow Emperor asked: "Do the Yin and Yang of the Luo Collaterals also correspond to their Meridians?" Qibo said: "The color of the Yin Luo corresponds to its Meridian, but the color of the Yang Luo varies without constancy, following the four seasons." This means the color of the Yin Luo corresponds to the Five Zang Organs, while the color of the Yang Luo corresponds to the Four Seasons. Yang is external, and Yin is internal.
If cold is excessive, blood coagulates and stagnates; when it stagnates, it appears green or black. If heat is excessive, blood becomes moist and lustrous; when it is moist, it appears yellow or red. These are all normal colors, referred to as indicating no disease. Because these changes are due to the season and not due to disease, they are also considered normal.
If all five colors are seen, it is referred to as Cold-Heat [disorder]. This is because it does not correspond to the seasonal cold or seasonal heat, hence it is regarded as a Cold-Heat condition.
The *Pi Bu Lun* (Treatise on Skin Regions) states: "Colors mostly green indicate pain; mostly black indicate Bi Syndrome (obstruction); yellow and red indicate heat; white indicates cold. If all five colors appear, it indicates mixed cold and heat." Generally, Yang Luo follows the seasons, with changes originating externally, which is the constant way of Heaven. Changes appearing due to disease originate internally, which is the variable way of humanity. Observing both time and disease allows one to understand the constant within the variable, and the variable within the constant.
As for the veins above both dorsum pedis being vertical, firm, or depressed, this indicates disease of the Foot-Yangming [Stomach] Meridian. Blood in the Yu Luo (collateral at the thenar eminence) indicates disease of the Hand-Yangming [Large Intestine] Meridian. Green Luo Collaterals at the hand Yu indicate cold in the Stomach. Red Luo Collaterals at the Yu Ji (LU10) indicate heat in the Stomach. Black pulse color at the Yu Ji may be a sign of Epilepsy. Sudden blackness indicates long-standing Bi Syndrome. Green and short collaterals indicate deficiency of Qi. Visible pulsation of the neck vessels accompanied by panting and rapid cough indicates Water retention. Blue veins rising between the ears indicate pulling pain. Full blue collaterals above the Wang Gu (GB12) behind the ear, with restless sleep, indicate Epilepsy. Many twitching vessels in the arm are called Blood Loss. Twitching of the vessel pulses over time leads to Wei Syndrome (flaccidity). Trembling and instability indicate Deficient Pulse. Scattered green and purple vessels on the face often indicate Wind-Heat disease. Scattered red and crimson vessels on the cheeks often indicate Pox/Smallpox disease. These are all Yin and Yang Luo Collaterals changing due to disease, and should also be observed in conjunction with time and disease.
However, I believe that Ying Nutrient Qi circulates within the vessels, and Wei Defensive Qi circulates outside the vessels. When Luo Collaterals appear, there should be blood color interspersed within them. Changes appearing on the left correspond to the left side; changes appearing on the right correspond to the right side; if seen on both sides, both sides are diseased. By observing which region and which color, one can determine which Zang or Fu Organ is diseased.
Regarding the appearance of the collaterals, there are differences in thickness, superficiality/deepness, length, and tension/laxity. Deductively speaking, thick collaterals indicate excess pathogenic Qi; thin collaterals indicate deficiency of Formative Qi. This is like how a large pulse indicates advancing disease, and a fine pulse indicates Qi decline. Superficial collaterals indicate disease in the exterior; deep collaterals indicate disease in the interior. This is like how a superficial pulse indicates the Exterior, and a deep pulse indicates the Interior. Long collaterals indicate regulated Qi; short collaterals indicate diseased Qi. This is like how a long pulse indicates regulated Qi, and a short pulse indicates diseased Qi. Tense/cramped collaterals indicate Cold; lax/relaxed collaterals indicate Heat. This is like how a tense pulse indicates Cold, and a relaxed pulse indicates Heat.
Therefore, based on the person's size, one determines the thickness of the collaterals; based on fat or thinness, one determines superficiality or deepness; observing seasonal cold or heat, one verifies tension or laxity; observing seasonal coolness or warmth, one verifies length or shortness. Observing these eight methods mutually, combining them with collateral color, and referencing pulse and symptoms, one can roughly comprehend their variations.
The Classic says: "Of these fifteen Luo Collaterals, Excess conditions will necessarily manifest, while Deficiency conditions will necessarily subside. Those appearing superficial and firm, or appearing large and bright, indicate abundant blood; those appearing fine and deep indicate deficient Qi." This is also the meaning here.
As for pediatric observation of the finger vein pattern, this is the Luo Collateral of the Hand-Taiyin [Lung] Meridian. For pox/disease observation, the tendons behind the ear are the Luo Collaterals of the Hand-Shaoyang [Sanjiao] Meridian. Both can be examined using these methods.