602 RICHARD GOLDSCHMIDT 



series of animals pictured in figures 4 to 19. Figure 38 shows a 

 practically female apparatus with the two laminae and the 

 ostium bursae, the first sign of abnormality being that the distal 

 end of the lamina is becoming pointed, which is characteristic 

 of the uncus. This pointed condition has progressed further in 

 figure 39, and still further in figure 40, where the laminae are 

 well on the way toward assuming the shape of an uncus. (The 

 asymmetrical condition of this organ js an abnormality often found 

 in intersexual specimens.) The chitinous segment-ring, char- 

 acteristic for the ninth male segment, is already in process of 

 formation. The same is seen in figure 41 where, furthermore, 

 the paired laminae are beginning to fuse at the base. The next 

 step, figure 42, shows a ring-like segment with an organ un- 

 paired proximally and paired distally, the ends being very 

 much like an uncus. The following figure 43 shows the trans- 

 forming process in progress and in figure 44 the uncus is almost 

 complete. And only now do the first rudiments of valvae ap- 

 pear, figure 45, more advanced in figure 46, showing a hook 

 in figure 47, and being almost complete in figure 48. There the 

 penis is present, also. The intermediate stages of its forma- 

 tion are not figured here. (See former publications.) 



A very important check for the correctness of our interpre- 

 tations can now be given. In the males the first organs to de- 

 velop are the valvae and penis, the last is the uncus. There- 

 fore, when males become intersexual, we should expect the first 

 change to appear in the uncus. This is in fact the case, as figures 

 49, 50, 51 show, where three types of intersexual males are rep- 

 resented. Everything is normal except the uncus, just becom- 

 ing paired in figure 49 (viewed from the side), more so in figure 50, 

 and beginning to assume the condition of a lamina in one of the 

 paired pieces in figure 51. 



Without going more into detail we can regard as proven the 

 general rule: A given organ develops, in the case of female in- 

 tersexuality, on female lines up to a given point, when suddenly 

 the male stimulus starts, and the rest of the development is 

 purely male. The degree of intersexuality is determined by how 

 long the development has been in .progress before the turning- 



