J 035 



Amitotic division. 



Most invesligalors believe, with Fi.emming, that mitotic cell division 

 is the only way in which a new growth in a healthy body can 

 take place. And it is generally admitted that amitotic cell division 

 occurs only in pathological tissues and, apart from this, only in 

 cells that have a very short life. As has been pointed out above, 

 the nerve cells are generally admitted to have a life equal in length 

 to that of the individual; it is therefore obvious that any idea of 

 an increase in these by amitotic division must be out of the (piestion. 

 And 1 must myself confess that the idea of the permanence and 

 high position of the neurones among the cells in general has become 

 so deeply rooled through studying handbooks of medicine as well as 

 the majority of special treatises on this subject that it is really 

 difficult to get accustomed to the idea that there may be another 

 possibility for the increase in the nerve-cells than mitotic division. 

 If, however, one comes quite freely, as I did, to the problem of 

 exi)laining the actually existing increase in the nerve-fibres during 

 the whole post-embryonic development, and finds that this explanation 

 has to be sought in an increase in the number of the neurones and 

 not in a cleavage of the axons — and this at the same time as one 

 finds signs of how a large number of the nerve cells are degene- 

 rating and dying away, then of course the new formation of ganglion 

 cells, even after mitoses no longer occur in these regions, must be 

 considerable. There are also in the central nervous system, as will 

 be described in more detail below, appearances that seem to indicate 

 that amitotic division of young cells really takes place there. Obser- 

 vations pointing in this direction have already been made and 

 described in literature, although this information seems to have 

 attracted but little attention. 



Rohdf/) described in 1896 how ganglion cells in invertebrates 

 increase by amitotic division. R. distinguishes four different types 

 of such a division in these animals. As invertebrates have not been 

 the object of my investigations in this matter, I cannot criticize 

 R's statements, although some of them seem somewhat strange. 



Paladino*) (1914) describes amitotic division of cells in the central 

 nervous system of vertebrates. P. states that the neurones degenerate 

 and perish, and in connection with this there is a new development of 

 nerve elements. There are good reasons for believing that this 



^) ROHDE, 1. c. 



2) Paladino, 1. c. 



