Endosperm of Hordeum vulgare during Germination. 17 



examined these cells during the germinative period has ever doubted 

 that they are actually living units.* 



The cytological evidence as to the state of the amyliferous cells 

 is not so clear, and we have been unable to find any record of a 

 systematic examination of the appearances presented by their proto- 

 plasmic contents. 



The difficulties of examination are, of course, much greater here 

 than they are in the case of the " aleurone-cells," owing to the 

 tightly packed starch-grains, which must be removed by some method 

 incapable of acting on the other cell-contents, which they completely 

 obscure. The ordinary reagents which are used for this purpose, 

 such as acids and alkalis, are quite inadmissible, and although much 

 better results are obtained with cold water extracts of malt, or of 

 animal pancreas, acting for some time at 40 50 C., there are objec- 

 tions to both of these agents. The malt extract often possesses some 

 cytohydrolytic power, which acts on the more delicate portions of 

 the cell-membrane, and destroys the coherence of the tissue, and 

 even when this objection is removed by previously heating the malt 

 extract to 60 65 C. for some time, malt-proteids are often preci- 

 pitated iii a finely granular form within the sections, and confuse the 

 results. 



An extract of animal pancreas is a very good solvent, for starch, 

 but since this possesses slight proteohydrolytic power in feebly acid 

 solutions, there is a danger of solution of the protoplasmic matrix 

 along with the starch ; and, moreover, when " liquor pancreaticus " 

 (Benger) is used, there is considerable precipitation at 40 46 C. 



No such objections, however, apply to the use of diluted and 

 filtered mixedf human saliva. With the addition of a little thymol, 

 to prevent putrefaction, this agent may be allowed to act on the 

 very thinnest sections of seeds at a temperature of 46 C. (the 

 optimum temperature for ptyalin) for many hours, without any 

 change in the sections other than the dissolution of the starch. The 

 starch-granules dissolve very completely, leaving sharply marked 

 lacunae in the protoplasm, which can then be stained in any desired 

 manner. 



In staining, we have used a mixture of iodine-green and fuchsine. 

 With this reagent the nucleus is stained green, and is strongly con- 

 trasted with the cytoplasm which takes up the red stain. 



* Tangl also observed the continuity of the protoplasm in the " aleurone-layer," 

 a continuity effected by means of fine threads passing through pores in the thick 

 walls of contiguous cells. Walter Gardiner (' Koy. Soc. Proc.,' vol. 52, 1897, 

 p. 100) has confirmed this, and informs us that he has also proved the existence of 

 continuity in the cytoplasm of the amyliferous cells. 



t By this is meant ordinary human saliva, consisting of the mixed secretions of 

 the three seti of salivary glands, 



VOL. Hill, C 



