CYTOPLASM AND NUCLEUS 



In my laboratory it was lately shown that the con- 

 sistence of chloroplasts is often very soft, very 

 much less solid than the nucleus. They contain a 

 mixture of two kinds of colloids, one of them which 

 swells in water, of hydroid character, the other 

 resembles fats and most probably contains the 

 green colouring matter or Chlorophyll. In life, 

 as we may think, the lipoid phase is distributed as a 

 very fine emulsion through the hydroid phase. 



There are some other small bodies which are free 

 from colouring matter, and which form starch 

 from sugar. We call all these protoplasmatic 

 organs which are in the service of carbohydrate 

 metabolism, Plastids. As far as we know, they are 

 never formed from other plasmatic parts. They 

 always take their origin from mother plastids by 

 cleavage. In some plant cells there have been 

 found special plasmatic bodies which form fat, 

 but more frequently fat is independently formed 

 in the fundamental plasma substance. We may 

 say the same of the protein substances of proto- 

 plasm. It may be, however, that for the formation 

 of all these compounds very small centres or 

 distinct organs exist, which cannot yet be recog- 

 nised even by means of the highest microscopical 

 power. In any case, the parts where the different 

 chemical changes take place must be separated 

 in some way from each other, to prevent mixing 

 with other substances. In colloid systems, as such 

 separating walls, we find membranes formed of 

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