14. =Of the Stomach.=--May be fatal from shock, from hæmorrhage, from extravasation of contents, or from inflammation. The danger is materially lessened by prompt surgical intervention.
15. =Of the Intestines.=--May be fatal in the same way as those of the stomach. More dangerous in the small than in the large intestines.
16. =Of the Kidneys.=--May prove fatal from hæmorrhage, extravasation of urine, or inflammation.
17. =Of the Bladder.=--Dangerous from extravasation of urine. In fracture of the pelvis the bladder is often injured, and extraperitoneal infiltration of urine occurs, with frequently a fatal issue.
18. =Of Genital Organs.=--Incised wounds of penis may produce fatal hæmorrhage. Removal of testicles may prove fatal from shock to nervous system. Wounds of the spermatic cord may be dangerous from hæmorrhage. Wounds to the vulva are dangerous, owing to hæmorrhage from the large plexus of veins without valves.
Stains may require detection on clothing, on cutting instruments, on floors and furniture, etc. The following are the distinctive characters of blood-stains:
(a) =Ocular Inspection.=--Blood-stains on dark-coloured materials, which in daylight might be easily overlooked, may be readily detected by the use of artificial light, as that of a candle, brought near the cloth. Blood-spots when recent are of a bright red colour if arterial, of a purple hue if venous, the latter becoming brighter on exposure to the air. After a few hours blood-stains assume a reddish-brown or chocolate tint, which they maintain for years. This change is due to the conversion of hæmoglobin into methæmoglobin, and finally into hæmatin. The change of colour in warm weather usually occurs in less than twenty-four hours. The colour is determined, not entirely by the age of the stain, but is influenced by the presence or absence of impurities in the air, such as the vapours of sulphurous, sulphuric, and hydrochloric acids. If recent, a jelly-like material may be seen by the aid of a magnifying-glass lying between the fibres. If old, a cinnabar-red streak is seen on drawing a needle across the stain.
(b) =Microscopic Demonstration.=--With the aid of the microscope, blood may be detected by the presence of the characteristic blood-corpuscles. The human blood-corpuscle is a non-nucleated, biconcave disc, having a diameter of about 1/3500 of an inch. All mammalian red corpuscles have the same shape, except those of the camel, which are oval. The corpuscles of birds, fishes, reptiles, and amphibians, are oval and nucleated. The corpuscles of most mammals are smaller than those of man, but the size of a corpuscle is affected by various circumstances, such as drying or moisture, so that the medical witness is rarely justified in going farther than stating whether the stain is that of the blood of a mammal or not. Unfortunately, the corpuscles are usually so dried that little information regarding their size can be given.