This section is from the book "The Sushruta Samhita", by Kaviraj Kunja Lal Bhishagratna. Also available from Amazon: The Sushruta Samhita.
The poison which is secreted with the saliva (of a spider) gives rise to non-shiftting superficial Kotha (urticaria) attended with itching and slight pain. The poison from a scratch with the tips of its claws, is attended with swelling, itching, horripilation and a sense as if fumes had been escaping from the body. Any part of the body coming in contact with the urine of a spider is marked by a (slight) blackness of skin in the middle of the point of contact and redness at its edge, and the affected part is cracked. In a case of fang-poison (actual bite) the seat of the bite is marked by fixed circular patches and becomes indurated and discoloured. The poison in this case is strong. A part of the body touched with the Rajas, semen, or with fecal matter of a (venomous) spider is marked by eruptions of pustules which assume a yellow colour like that of a ripe Amalaka or Pilu. 47.
Thus far we have described the effects of spider-(Lutâ)-poison according to its seat in the body of the insect and to the period of its aggravation. Now we shall describe the mythological accouut of the origin of these insects and the curable and incurable natures of their bites together with the course of medical treatment to be followed in each case. 48.
Once upon a time, it is said, king Vis'vámitra went to the hermitage of the holy Vasishtha and by his actions aroused the wrath of the holy sage. Drops of perspiration were thereupon produced on the forehead of that holy and celestially brilliant sage and trickled down on the stacks of hay culled and gathered (Luna) by the holy sages for the use of the (celestial) cow, and behold they (the drops of sweat) were transformed into innumerable dreadful and venomous spiders (Lutá) which, up to this day, are found to infest the articles of royal use for the iniquity of that royal sage (Vis'vámitra). They are called Lutás (spiders) from the fact of their being germinated from the drops of perspiration of the holy sage Vas'ishtha fallen on the culled (Luna) stacks of hay and they are sixteen in number. 49.
The poison of spiders is divided into two classes - curable with difficulty and incurable. Of the sixteen kinds of spiders, the bites or poisons of eight may be cured with the greatest difficulty, while those of the remaining eight are incurable. The Tri-mandalá, Svetá, Kapilá, Pitiká, Ala-vishá, Mutra-vishá, Raktá and the Kasaná are the eight species of spiders which belong to the first group. A bite by any of them is attended with an aching pain in the head, pain and itching about the seat of the bite and the symptoms and disorders peculiar to the aggravated Váyu and Kapha. The Sauvarniká, Lája-varná, Jálini, Eni-padi, Krishna-varná, Agni varná, Kákándá and the Málá-guná belong to the second group and their bites are marked by bleeding, fever, a burning sensation, dysentery and disorders due to the concerted action of all the three deranged Doshas of the body, and the bitten part putrefies. Eruptions of various sorts and pustule; and large circular patches as well as large, soft and shifting swellings, red or brown in colour, appear on the skin about the affected part. These are the general features of spider (Lutá)-bites. Now we shall describe the characteristic symptoms which are developed by bites of the several classes of spiders and the course of medical treatment to be adopted in each case, 50-51.
 
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