42 Life and Death, Heredity and Evolution 



as in higher animals and ourselves, the progeny produce 

 anew their peculiar characteristics. The problem of heredity 

 is : Why should they produce the same sort of characteris- 

 tics that their parents produced? The problem is of just 

 the same sort in the Protozoa that it is in ourselves. In such 

 a case as Difflugia the answer which suggests itself takes 

 something of this form : the offspring produce the same sort 

 of shell that the parents did, because they are made of the 

 same sort of material. This answer is indeed little but a 

 form, but it is a form into which a more complete answer 

 will have to fit. 



Before inquiring further as to just how closely the off- 

 spring do produce the same characteristics as the parents, 

 let us look at another example or two, showing in a still 

 more marked way the nature of inheritance. In some of the 

 more complex Protozoa, such as the hypotrichous infusoria, 

 we find that the body bears a great number of organs of 

 definite form and number, arranged in a precise manner. 

 Observe in this Stylonychia (Figure 13), the numerous leg- 

 like or fin-like appendages, for creeping or swimming. When 

 the animal reproduces, it divides cross-wise, and if it merely 

 divided without any rearrangement of parts, you can see 

 that the two progeny would be most unlike the parents. As 

 a matter of fact, during reproduction all these organs dis- 

 appear; they are apparently gradually absorbed into the 

 body. Then on each half of the body there appears (even 

 before the disappearance of the old organs) a new group 

 of minute projections (Figure 13, B), all close together; 

 not arranged at all as were the appendages of the parent, 

 and not showing the differences of size and structure that 

 were found in the parent. These small projections now 

 proceed to change place, scatter themselves, and take up 

 positions corresponding to those of the appendages of the 



