IT is only a relatively short time since we assu. med that plants only could synthesize complex compounds whereas animals were forced to obtain these complex compounds indirectly from plants and that in modifying these complex compounds for their specific needs only slight chemical changes are necessary. One of the most complicated substances in the animal body is cholesterol. It is a hydroaromatic secondary alcohol with 27 carbon atoms containing tw'O combined six carbon-rings, one five carbon-ring, a side chain and one double bond. It is, therefore, not surprising that this knowledge of the constitution of cholesterol led to the assumption that the animal body was forced to obtain this or a similar substance from plants because we could not conceive of synthetic activities of that order in animal tissues. However, cholesterol-balance studies by