On a fat-soluble growth factor required by blow-fly larvae

ALTHOUGH there is good evidence that insects require vitamin B [see Uvarov, 1928; Hobson, 1933], little is known of their need for fat-soluble growth factors. The previous work will not be reviewed in detail at this stage, except to say that the suggestions of some workers that insects require vitamin A or E have little foundation. The present work arose from the observation that filtration of peptic digests of meat removes a substance which is essential for the growth of blow-fly larvae (Lucilia sericata Mg.) and which occurs in certain fats. An investigation was therefore made of the distribution and properties of the active substance.