10 



The crystals will he ol' tiie same form :inil size as those 

 luadi' rtdiii inaninialiaii hlooil. Tei<']iiiiaiiirs crystals can 

 he ohtaiued from blood stains no matter how old, hence their 

 ]»resence is often of value in medico-legal cases. Romem- 

 her tiiat tlie fact thatTeichmann's crystals can he obtained 

 from a stain only shows the presence of Itlood and nothing 

 more; tiiey can be obtained from the luemoglobin of any 

 red 1)1 00(1 cell. 



(d) Detection of Red Blood Cells in a Dry Clot 



of Mammalian Blood. 



Take :i siu;ill poition of a dix- clot, ]ilace it on :i sliile, an<i 

 cover it witli several drops of a ;;.']%' solution of ]K)tassinin liydrate. 

 After the clot lias become soniewiiat softened, break it no into as 

 small pieces-'as possible with yunr tcasintc needles, and cuver witii 

 a cover trlass. Set it aside for 5 to 10 iniimtes, then trentiy tap the 

 cover glass with a teasing needle. 



Examine to see whetlier any of the cor|)tiscles are free; 

 if so, determine their sliape and size; if not set aside 

 awhile and try again. 



(e) Detection of Red Blood Corpuscles in a Drj'- 



Clot of Pigeon's Blood. 



Prepare as (il) of this lesson. 



Search for the oval red lilood cells; yon may be able 

 to make out a nucleus in them. 



