Slide showing Figure 3 which concerns X and Y chromosomes and sex determination. Slide shows Figure 3 which concerns X and Y chromosomes and sex determination. The text under figure 3 reads: 'In the following, however, we presuppose that the X and Y chromosomes have the same values as in the example given above. The question is merely to clear up the underlying principle of the sex determination; the absolute values are, therefore, of minor importance in this connection. We further presuppose - what does not necesarily have to be the case - that the autosomal sex genes which appear in these masculine races are the same as those present in the first mentioned.' Late 19th to early 20th century