Journal of Applied Microscopy. 



51 



Figure 7. — Photo-micrograph of the first division of the endosperm 

 nucleus of Lilium tigrinum. Preparation by Mr. O. W. Caldwell of the 

 University of Chicago ; magnification, 1600 diameters. The interzonal 

 fibers are well shown and seem to interweave at the plane of the equatorial 

 plate. No detail in the chromosomes is shown, on account of the intense 

 staining. Cells of the nucellus are also shown. 



Figure 8. — This preparation is one of Dr. Chamberlain's, illustrating 

 a stage in the first division of the macrospore nucleus of Lilium phila- 

 delphicum. The magnification is the same as in figure 7, viz., 1600 diam- 

 eters. The nuclear spindle has the appearance of being bipolar. In the 

 negative, and direct prints therefrom, may be seen at one of the polar 

 fields a series of outward radiating lines composed of minute dots. The 

 chromosomes are grouped in the equatorial plane. The growth of the 

 drawing fibers of the nuclear spindle directly into the chromosome is 

 clearly shown, and is illustrative of the theory of fibrillar contractility, 

 by means of which the chromosomes are drawn apart along the line of the 

 spindle fiber, leaving the interzonal fibers as shown in figure 4. 



Wheat Flour in Ground Ginger. 



A. McCll.L, Ji. A., B. ^c. 

 Assistant Analyist to the Inland Revenne, Canada. 



The most common adulterant of ground 

 ginger is wheat flour. The identification 

 of this adulterant, as well as its quanti- 

 tative estimation, are best made by the 

 microscope. 



Seen by plain light, the granules of 

 ginger starch are ovoid, the markings 

 (hilum, concentric rings, etc.) being very 

 indistinct. In these respects they are 

 scarcely to be distinguished from wheat 

 starch, although the markings on the 

 latter may be generally made out by 

 very careful focusing and management 

 of the light. 



The most obvious distinction is the 

 very great difference in size between 

 the largest and the smallest of the wheat 

 granules, while the limits for ginger 

 starch are less wide. One does, however, 

 find very small ginger granules, and the 

 average size (20 to 25 Mkm.) is not far 

 from the average size of wheat. 



I have made attempts to determine the 

 percentage in each kind of known mix- 

 tures by counting in five fields, using 

 plain light, and have found the results 

 very unsatisfactory, owing to the un- 

 certainty in identifying the visible 

 granules. The attempt also involves the 

 expenditure of much time. When polar- 

 ized light is used, a cross appears in the 

 granules of each kind of starch; but 

 while this is quite symmetrical in the 

 case of wheat, it is distinctly asymmet- 

 rical in ginger. By carefully focusing 



into the plane of a wheat starch granule, 

 the granule is seen to be divided into 

 four exactly equal portions by the dark 

 cross; when the focal distance is a little 

 higher or lower, the cross is still sym- 

 metiical bilaterally, and the alternate 

 segments are alike. (Fig. 1.) 



In the case of ginger starch, the cross 

 divides the granule so that a very small 

 segment is complemented by a very large 

 segment, from which it is separated on 

 each side by segments quite like each 

 other, and intermediate in size between 

 the first two. When the focusing is not 

 perfect, the appearance may resemble 

 oyster shells with the valves a little 

 apart (Fig. 2), but the general resemb- 

 lance is to a beetle with elytra expanded. 

 (Fig. 3.) 



There is no difficulty whatever in dis- 

 tinguishing between wheat and ginger 

 stai'ches seen in this way, and I have 

 found it quite easy to determine within 

 two to five per cent, the amount of each 

 kind in mixtures of the two (Fig. 4) by 

 counting the visible granules of each 

 kind in five fields using a power of about 

 two hundred diameters. 



It is, however, less fatiguing to the eye 

 and more satisfactory, as furnishing a 

 permanent record of the sample, if pho- 

 tographs be made from carefully pre- 

 pared mounts. 



I have found glycerine to give the best 

 results when the stage is used horizon- 



