On a nematode found in the stomach of a copper-head snake / by D. McAlpine.

  • McAlpine, Daniel, 1848-1932.
Date:
1891
Catalogue details

Licence: Public Domain Mark

Credit: On a nematode found in the stomach of a copper-head snake / by D. McAlpine. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    In the tirst fraction, referring to the pharynx, the numerator (•1) denotes the distance from the anterior extremity to the base of the pharynx, or buccal cavity, and the denominator (•2) represents the diameter of the body at the base of the pharynx. In the second fraction, relating to the nerve-ring, the numerator (-5) denotes the distance from the anterior extremity to the centre of the nerve-ring, while the denominator (-3) indicates the body diameter passing through the nerve-ring. In the third fraction, referring to base of neck, the numerator (3'6) denotes the distance from the anterior extremity to the posterior end of the oesophagus, or base of the neck; or in other words, is the length of the head and neck combined. The denominator (5) represents the diameter of the body at the point of junction of the oesophagus and intestine, or where the neck joins the body. In the fourth fraction, relating to the vulva, the numerator (67) denotes its distance from the anterior extremity, and the denominator (I'2) the diameter of the body there. A further reference is introduced here, placed above and to the i*ight of the numerator, to indicate the percentage of the body occupied by the sexual organs. The number 37 indicates that they occupy 37 per cent, of the entire length of the body, or more than one-third. In the fifth and last fraction, relating to the anus, the numerator (99 '75) denotes its distance from the anterior extremity, and the denominator (4) the diameter of the body there. It must be clearly understood that relative dimensions and not absolute measurements are given, for relative and not absolute sizes are of prime importance for systematic purposes. However, if the actual measurements are desired, they may easily be calculated by dividing the body length, 14-i mm. by 100, which gives the unit of length for the various parts. This unit is 1'4-i mm., and the absolute lengths will be as follows :— Body length .. .. 144 mm. Length of head .. .. .. .. -144 mm. Length of neck .. .. ' .. .. 5-040 „ Length from base of neok to vulva .. 91*296 ,, Length from vulva to anus .. .. 47-160 ,, Length of tail ..' -360 „ 144' mm.