-236 Marquette, 3Ianifestations of polarity in plant cells which usw. 



of the preparations suffices to sliow that the cell contents here 

 present relations which are of the greatest interest with reference 

 to the question of the Organisation of the cell. Usually the cells 

 of these young leaves contain starch, frequently in considerable 

 abundauce, and one is at once Struck by the fact that the starch 

 grains are collected in masses of which there are apparently 

 without exception either one or two in a cell. In preparations 

 treated with the triple stain these starch masses on acconnt of 

 the deep blne of the starch grains present a striking appearance. 

 Equally conspicnous is the fact that the starch masses bear in 

 every case a definite relation to the nucleus and that in resting 

 cells there is without exception only one starch mass present which 

 lies closely pressed against the side of the nucleus, while in the 

 later stages of division there are just as regularly two masses 

 present which in this case are invariably placed at the poles of 

 the spindle and later in polar depressions of the young daughter 

 nuclei. All this is to be observed, as it were, at a glance. 



More detailed study shows that the starch-grains lie in a 

 clear space which is surrounded by a more or less distinct bound- 

 ary. Frequently it appears as though a well defined membrane 

 surrounded the mass of starch grains, a membrane of varying 

 thickness, or, possibly, a membrane of uniform thickness which 

 appears thicker in places because of the irregulär deposition of 

 fine particles upon its surface. In general the walls bounding the 

 starch masses appear thicker than those of ordinary vacuoles, in 

 other cases, however, it is almost impossible to distinguish a 

 definite bounding layer. But even in these cases the starch con- 

 taining area Stands out froni the rest of the cytoplasm owing to 

 the abrupt ending of the lamellae or Strands of the cytoplasm at 

 the surface of this areas. Frequently, too, if inuch starch is present, 

 the outlines of the enveloping layer are clearly indicated by the 

 Position of the outermost grains since the group of crowded starch 

 grains closely follows the contours of the envelop which holds them 

 together. (Fig. 2.) 



If the contents of these starch bodies is examined more closely, 

 it appears that, in many cases at least, it does not consist entirely 

 of starch grains but that in addition to these there are Strands 

 (which stain blue-black with the triple stain) of varying thickness 

 extending between the starch grains and between these and the 

 periphery of the body. There also appear to be small granules 

 taking the red stain scattered between the starch grains, they 

 cannot, however, be distinguished with certainty froni minute starch 

 grains in preparations stained with the triple stain. The presence 

 of small granules other than starch can, however. be easily de- 

 lnonstrated in iron-haematoxylin-preparations. In these the starch 

 grains are almost colorless, but the other granules take a deep 

 black stain so that they stand out sharply in the otherwise 

 clear space. 



These starch-containing bodies appear in varying forms and 

 it is noticeable at once that their starch content nuctuates. This 



