Diatom test is used to diagnose death due to -

Ans. is 'b' i.e., Drowning PM findings of drowningExternal findingsA)Specific (diagnostic)i) White, fine, lathery, abundant and tenacious froth at nose and mouth which increases on chest compression.ii) Weeds, grass, plants, mud or stones in tightly clenched hands.B)Non-specifici) Washer woman hand and feet.ii) Cutis anterina (goose skin).iii) Half opened eye with dilated pupil and congested conjunctiva.Internal findingsA)Specific (diagnostic)i) Water in stomach and intestine.ii) Diatoms in bone marrow and brain.B)Non-specifici) Emphysema aquosum.ii) Palatauf s hemorrhage (subpleural hemorrhage).* Diatoms are unicellular algae, suspended in water. They have silicaceous cell wall (i.e. cell wall contains silica) which resist acid digestion and putrefaction. Only live body with a circulation can transport diatoms form lung to brain, bone marrow, muscles etc. So, presence of diatoms in brain and bone marrow indicates death due to drowning. For detection of diatoms, bone marrow of long bones, e.g. femur, tibia, humerus or sternum is highly suitable and reliable. As diatoms resist acid digestion, to extract them acid digestion techinique is used. Diatoms test is negative in dead bodies thrown in water and in dry drowning. However, diatoms test is invalid, if deceased had drunk this water before submersion or species of diatoms do not match with specimen from the site of drowning.