§ 2 SPECIFICITY OF THE OVIPOSITOR TEST 7 



substances may be present in the preparation to be tested, 



and especially the solvent itself. 



According to DUYVENE DE WiT, the following substances 



were inactive:— 



Yohimbine 2 mg per 750 ml water 



Cholesterol 5 ,, ,, 750 ,, 



Digoxigenin 6 ,, ,, 750 ,, 



Ergosterol 10 ,, ,, 750 ,, 



Vitamin D2 2 ,, ,, 750 ,, 



According to VAN KOERSVELD, the following substances 

 were inactive: — 



One should, therefore, take the greatest care when selecting 

 the solvent. We generally use ethanol, which does not interfere 

 significantly with the reaction when administered in a maxi- 

 mal quantity of 0.5 ml per 750 ml water. Propylene glycol, 

 also a suitable solvent for steroid hormones is, considerably 

 less active than ethanol, and is therefore useful. Veratryl- 



