74 



MOKBID GrvOAVTH IN GENERAL. 



The physiological cell-growth which accompanies or causes 

 the growth of the entire oi*ganism, seems to be confined to such 

 cells only as are either destitute of a limitary membrane, or 

 furnished W'ith a mere " physical investment " of extreme deli- 

 cacy. Under these conditions fission of the cells, like that of 

 their nuclei, manifests itself as a constriction and subsequent 

 division of their body (fig. 28). The longitudinal splitting of the 

 fibres of striped muscle is only a variety of fission. 



To this mode of cell-division by fission, morbid histology adds 

 two further types, or, to speak more correctly, two modifications 

 in the anatomical features of the process. These are, the develop- 

 ment of cells in nucleated protoplasm, and endogenous cell- 

 formation. 



The first of these presupposes two anatomical conditions ; the 

 parent-cells must be quite devoid of a limitary membrane, and a 

 considerable number of such wholly naked cells must be aggre- 

 gated together. Under these circumstances the protoplasm of 

 any cell will seem to be uninterruptedly continuous with that of 

 neighbouring cells; the outlines of separate cells are not dis- 

 tinguishable ; and this of course applies equally to the outlines of 

 the newly-formed cells. Should such cells divide, our only way 

 of detecting their division would be by noticing that two nuclei, 

 resulting from the fission of a single one, and originally in close 



Fig. 28. 



Fig. 29. 



Cells undergoing fission, a. 

 From a luxuriant granula- 

 tion; h. Division of fibre 

 of striped muscle. 





Nucleated protoplasm : frag- 

 ment of a granulation. 



contact, have moved away from one another to a slight extent. 

 Vie cannot actually sec more than the various stages in the 

 division of the nuclei. 



We find this nucleated j^rotoplasm in the most luxuriant forms 

 of cell-proliferation, such as granulations, soft cancer, and sar- 



