COCHINEAL 533 



the silver grain is usually attributed to the waxy matter that covers 

 the insects and has not been melted by heat ; it appears, however, 

 to be largely due to inorganic matter. 



Adulterants. Cochineal is frequently adulterated by the addition 

 of inorganic matter such as talc, barium carbonate and sulphate (for 

 silver grain cochineal), or manganese dioxide, lead sulphide, magnetic 

 iron sand, &c. (for black grain cochineal). These can readily be 

 detected by means of the ash which should not exceed 6 per cent., 

 genuine cochineal of good quality yielding generally about 2-5 per 

 cent. Silver grain cochineal, heavily ' dressed,' may yield up to 

 50 per cent, of ash. 



ANIMAL GLANDS 



DUCTLESS GLANDS 



The ductless glands include a group of organs of very varied functions. 

 They have no special ducts to convey their secretions either into 

 the digestive tract or elsewhere. They do, however, form substances 

 which pass directly into the blood stream or into the lymph channels. 

 These substances belong to the class of bodies known as hormones, 

 which are also formed by organs such as the pancreas which discharge 

 their secretions externally. The presence of these hormones in the 

 body is in many cases essential to health and even to life, and the 

 activity of the ductless glands is correlated with and regulates the 

 functions of distant organs, the only link being the blood by which 

 the hormone is carried from its place of origin to its place of action, 

 each hormone exercising a specific function in exciting the activity 

 of a particular organ or tissue. Those which have been studied are 

 of comparatively simple nature, dialy sable, readily soluble in water 

 and not destroyed by boiling. 



The chief ductless organs employed in modern medicine are the 

 thyroid and parathyroid glands, the suprarenal glands, the pituitary 

 body, the spleen and the thymus. 



SUPRARENAL GLAND 



The suprarenal gland is a small, ductless, glandular organ situated 

 above the kidney. It consists chiefly of an outer yellowish portion 

 or cortex and an inner darker portion or medulla. This inner portion, 

 and extracts made from it, possess remarkable haemostatic properties 

 which are due to a crystalline body, adrenalin or adrenin, which is 

 present in very small proportion. This substance has been prepared 

 synthetically in the form of a pale buff- coloured crystalline powder, 



