Part B. Mixtures and Adulteration of Grass "Seeds." 



2. Certain simple mixtures of grass "seeds," mixed and supplied by the teacher, will be 

 given you. After identifying and recording what you find in the mixtures, check the list of 

 "seeds" you actually find present with the list oi "seeds" which your instructor says you 

 should find. If the two lists do not agree note where the disagreement is, and if possible 

 find the cause of error. If you are mistaken in the identity of any kind of "seed," study 

 that "seed" very carefully so that the same mistake will not be made again. 



Remember that one or two "seeds" of any species in a mixture may easily be there by 

 accident. In fact, samples of "seed" are seldom absolutely free from a very few "seeds" not 

 supposed to be present. If any kind of "seed" belongs in the mixture it should be there in 

 considerable quantity. If you find a very few "seeds" which you suspect are not supposed to 

 be in the mixture, record the presence of such "seeds" as "a trace." It is also best to put 

 these doubtful "seeds" aside so they may be examined again, if necessary. 



It is suggested that before attempting to name the various "seeds" in a mixture, you sep- 

 arate into various lots all the different kinds of "seed" which you find present. It is often 

 much more difficult to identify a doubtful "seed" in a general mixture than it is when placed 

 near a number of already identified "seeds" supposed to be of its own kind. 



3. If the foregoing exercises in simple mixtures have been carefully worked out, you are 

 now ready to identify the "seeds" in the various "Prepared Mixtures of Grass 'Seeds.' " Not 

 only are you expected to identify the "seeds" in each mixture but you are to give the approx- 

 imate proportions (expressed in percent) of each kind of "seed" present. It will be sufficiently 

 accurate for our purposes to estimate the percent of the different "seeds" present. If you 

 are given a representative sample of the prepared mixture and in turn work with a repre- 

 sentative part of this sample, the separation of a small lot of "seed" will indicate approxi- 

 mately what was in the whole original mixture. 



Record in definite form just what "seeds" you find in each prepared mixture — also the 

 percent of each kind of "seed." 



106 



