270 THE UNFERTILISED EGG AS A [pt. iii 



corvinin and corvinidin, in the egg of the crow. It is not certain, 

 however, to which of the well-known proteins of the hen's egg-white 

 these others correspond. Judging from the percentage composition 

 tables in Table lo a, the columbin of the dove's egg corresponds 

 to hen ovoalbumen and to duck anatinin, while duck anatin corre- 

 sponds to hen ovomucin, but in the absence of definite information 

 the question must be regarded as unsettled, and would repay further 

 investigation. 



The minimal molecular weight of ovoalbumen, according to 

 Cohn, Hendry & Prentiss, is 33,800 (Marrack & Hewitt suggest 

 43,000), and its percentage composition is seen in Table 10 a; 

 the best analyses are probably those of Osborne & Campbell, 

 who give an account of its general properties. It has been further 

 analysed by several workers who have determined the proportions 

 of its constituent amino-acids, and whose results are seen in 

 Table 11. The hydrolyses of Osborne, Jones & Leavenworth; 

 Osborne & Gilbert, and of Abderhalden & Pregl were all done by 

 acid, but those of Hugounenq & Morel and Skraup & Hummel- 

 berger were alkaline, the former using baryta. The figures agree 

 accordingly, and all that can be said of them is that for purposes of 

 calculation the amounts of amino-acids must be taken as minimum 

 in each case. Attention may also be drawn to the less complete 

 analyses of Chapman & Petrie and Hugounenq & Galimard and to 

 the analysis of mixed egg-white proteins by Plimmer & Rosedale, 

 using the van Slyke technique. The large amounts of hexone 4Dases 

 found by them contrast with those found by the remaining workers, 

 using direct isolation, and if this is not due simply to difficulties of 

 technique it may lead us to expect a high content of hexone bases 

 in conalbumen and ovomucin when they come to be analysed. 



In Table 10 a the results obtained by Gupta on the hydrolysis pro- 

 ducts of ovoalbumen are given (see also Rudd). It is noticeable in 

 them, as in the analyses of ovoalbumen itself, that they contain 

 a high proportion of sulphur, though not so much as ovomucoid. 

 The spontaneous evolution of hydrogen sulphide by egg-white 

 on standing has long been known, and was made the subject 

 of a paper in 1893 by Rubner, Niemann & Stagnita, who found 

 that 100 gm. of egg-white gave off when boiled with water 10-7 mgm. 

 of HgS. Hausmann later decided that its source must be some labile 

 sulphydryl grouping in the ovoalbumen molecule. In 1922 Harris 



