Nutrients 111 



either before or after sterilization. Experiments 

 involving omission or reduction in concentration 

 of the constituents of this nutrient itself (salts, 

 sugar, thiamin, etc.) require the setting up of 

 special nutrients. While this approach is familiar 

 to all physiologists and experienced workers may 

 have their own methods of preparing such nutri- 

 ents, it seems desirable to outline briefly the 

 simplified procedures developed here. Three ex- 

 amples will be given. 



Each of the three sets of experiments outlined 

 above involves a comparison of 16 different solu- 

 tions, each provided in a quantity of one liter. 

 Since 50 ml. of nutrients are used for each culture 

 (see later), this provides 20 replications in each 

 nutrient. By employing condensed records of this 

 sort and simplified procedures, two men working 

 together can easily make up nutrient for 15 or 20 

 sets of cultures in a half day, which is about the 

 maximum that can be satisfactorily inoculated 

 and measured in a day. Sets of 16 have been 

 found most practical. 



Nutrients containing special ingredients not dis- 

 cussed here may require special treatment which 

 the individual worker will have to adapt to his 

 particular needs. 



Summary 



Nutrients for plant tissue cultures are for the 

 most part made up of definitely known synthetic 



