7 



8 



All figures after Castle 



PLATE III. UNIT CHARACTERS 



Tig. 1. A wild gray rat. Fig. 2. A hooded rat with the hood much reduced by selection. 

 Fig. 3. A normal hooded rat. Fig. 4. A hooded rat with the hood much extended by selec- 

 tion. Figs. 5 and 6. Grandchildren from such animals as those shown in Figs. 1 and 2, 

 which they respectively resemble. Their parents were like the rat shown in Fig. 1. Figs. 

 1 and 8. Grandchildren from such animals as those shown in Figs. 1 and 4, which they 

 respectively resemble. Their parents were like the rat shown in Fig. 1. 



