MESENCHYME CELLS OF TISSUE CULTURES 439 



The question as to just how the potassium permanganate 

 brings about these changes in the nucleus is a difficult one and 

 not to be answered easily. In the first place, the changes are not 

 specific for potassium permanganate, as they are sometimes seen 

 in cells that die in untouched cultures. In the latter condition 

 they take place much more slowly; they cannot be followed 

 from minute to minute, but consume hours or even days. The 

 most obvious explanation is one of increased permeability, asso- 

 ciated with an increased oxidation of the nuclear material and 

 breaking down of some of it, accompanied by a coagulation and 

 clumping of the chromatin material. This may account for the 

 mottled appearance and increased visibility of the nucleus and 

 the final aggregation of the chromatin into a compact mass. 



Hogue'^ found that when cells were treated with hypertonic 

 solutions they took up fluid and that the nucleus frequently gave 

 rise to a vacuole as an outlet for the extra amount of liquid 

 absorbed. No accompanying shrinkage of the chromatin mate- 

 rial was noted, however,- such as occurs in the potassium-per- 

 manganate experiments. 



CHANGES IN THE MITOCHONDRIA 



The mitochondria usually began to show changes after the 

 nucleus had been affected, at about the time that the nuclear 

 vacuoles appeared. Before the potassium permanganate was 

 added, the mitochondria were in the form of threads, rods, and 

 granules. A cell might contain any one or all of these forms. 

 Potassium permanganate caused the mitochondria to gradually 

 assume a spherical form, and the size of the spheres varied accord- 

 ing to the length of the mitochondrium from which each one 

 arose. The small circles in figures 1 to 16 represent spherical 

 mitochondria. The threads gave rise to large vesicles, the short 

 rods to small ones, and the granules to still smaller ones. The 

 long threads sometimes broke up into short threads before they 

 rounded up. Cells which contained both long and short mito- 

 chondria showed both large and small vesicles. Ones with long 



* Hogue, Mary J. 1919 The effect of hypotonic and hypertonic solutions on 

 fibroblasts of the embryonic chick heart in vitro. Jour. Exper. Med., vol. 30. 



