HEREDITY 



certain cases there is abundant opportunity tor the proto- 

 plasm to become more or less altered during the compli- 

 cated changes that accompany the division of the cell- 

 nucleus. This is notably the case in the chromosome re- 



FIG. 36. Graft of tomato (Lycopersicum esculenlum) on tobacco 

 (Nicotiana tabacum). On the tomato are grafted Solanum nigrum, S 

 integrifolium, and Physalis Alkekengi. (Graft made by Mr. M. Free.) 



duction divisions preceding spore-formation in the sporo- 

 phytes of higher plants (p. 37), especially when the plant is 

 a hybrid; and in spore-formation in the sporangia produced 

 from the zygospore of some of the filamentous fungi, like 

 Rhizopus or Mucor, the common black mold of bread. In 



