Heredity in Protozoa 41 



course that the new individual should have a shell just like 

 that of the parent. Its shell is produced anew. The parent 

 shell may have a peculiar form or structure ; in some cases 



Figure 12. Two parents, with their offspring, just before separation, 

 in Difflugia corona. The parents are above, the offspring (slightly 

 lighter in shade) below. After Jennings, 1916. 



for example, as you see in Figure 12, it bears spines of a 

 certain length and form and in a certain number. There is 

 no simple evident reason why the progeny should produce 

 a shell of the same form, with spines of the same length and 

 number. These things are not by any means merely handed 

 on bodily from parent to offspring. On the contrary, just 



