HOMOLOGOUS AND HETEROLOGOUS DEVELOPMENT. 447 



rapidly takes place, and generally in such a way, that 

 the originally single nuclei at once divide into a consi- 

 derable number of smaller ones, which at first remain 

 coherent. But in pus it is not certain whether the divi- 

 sion of the nucleus is succeeded by a real division in the 

 cell, whilst in other new-formations this is certainly the 

 case only the complete division, or if you will, the 

 cleavage, of the cells is delayed for a long time, and 

 this intermediate stage of the mere division of the nu- 

 clei continues for a disproportionately long period, and 

 seems to occur in some sort independently. 



These two plans are the ones regularly followed by all 

 those kinds of new-formations which do not directly lead 

 to hyperplasia ;* the normal condition is here in the first 

 instance interrupted by an intermediate state, in which 

 the tissue appears essentially changed, without one's 

 being able straightway to determine whether a growth 

 of a benignant or malignant nature will be developed 

 out of it. This is a stage of seemingly absolute indif- 

 ference ; from the appearance of the individual ele- 

 ments it cannot at all be inferred what their real destiny 

 is ; they behave exactly like the so-called formative celFs 

 of the embryo, which also at first exactly resemble one 

 another, no matter whether a muscular or nervous ele- 

 ment, or anything else, is about to proceed from them. 

 Nevertheless I regard it as very probable that delicate 

 internal differences do really exist, which to a certain 

 extent determine beforehand the subsequent metamor- 

 phoses not merely potential differences in the forma- 

 tive cells, but really material differences, only of so 



* There are processes which begin with Hyperplasia and end with Heteroplasia, 

 and others again, which begin with Heteroplasia and end with Hyperplasia. The 

 new formation of vessels, for example, never begin straightway with the formation 

 of vessels, but first of all cells are formed (heteroplasia), and afterward vesse Is (hy- 

 perplasia) are developed out of these cells. From a, MS. Note by the Author. 



