30 



II. FOOD RESERVES IN SITU. 



The "skin" is formed of dead cells pressed closely together (p), 

 and represents the combined pericarp of the fruit and spermo- 



derm of the seed ; under 

 it lies a layer of rect- 



CSllI^-~ j/r angular cells, which are 

 densely filled with small 

 aleurone grains (al). The 

 7 aleurone grains are em- 

 bedded in a finely gran- 

 ular ground substance. 

 Then follow elongated, 

 }-am less regular cells, which 

 contain large and small 

 starch grains. 



Mounting in Glycer- 

 ine-jelly. We will now 



FIG. 12. Cross section through a grain of wheat " mount " a successful 

 (Triti&im rulgare). p. pericarp of fruit ; t, testa of f - n o f f u p w V)pat 

 seed. In the endosperm cells succeeding -to these: sectior 



al, aleurone grains; am, starch grains; n, nucleus grain, SO as to learn how 

 ( x 240) 



to put up a permanent 



preparation, or, to use the common phrase, how to permanently 

 "mount" a preparation. We will employ at first the simplest 

 method of preparation, which gives a very satisfactory result, 

 and enclose the section in glycerine-jelly. Place upon the object- 

 slide so much of this jelly-like substance as we believe will suffice 

 to form a drop. Then warm the slide slowly over the flame of a 

 spirit-lamp, till the jelly has become fluid. It is very easy to 

 take too much glycerine-jelly; if so a little can be removed, when 

 fluid, with blotting-paper. In order to be able to choose a suit- 

 able quantity of jelly it is good to melt a quantity, and pour it 

 out to harden in a thin layer on a plate ; then with a sharp knife 

 cut it into tiny cubes of various sizes. These can be kept in 

 a closed bottle ready for use. If the jelly is taken each time 

 from the original bottle, a needle will serve to cut out a suit- 

 able scrap. When, in time, the surface of the jelly gets much 

 broken, the whole may be remelted by plunging the bottle into 

 hot water, so as to remove the entangled air. Under any cir- 

 cumstances the selection of a piece of suitable size requires 

 judgment, the necessary size varying with the size of the cover- 

 glass to be used and the thickness of the section to be enclosed. 

 The section is then laid in the melted drop, and a cover-glass 



