iS6 THE MICROSCOPE. 



portion of the cortex. Lying next this tissue, which may be de- 

 signated as liber, is a narrow ring of cambium, somewhat more 

 prominent than the same structure in Apocynum cannabinum, but 

 in the dried root somewhat difficult to resolve into its cellular 

 elements. It appears, however, to be, when fresh, made up of very 

 delicate, thin-walled, nearly spherical cells; or, in other words, it 

 presents no peculiarities distinguishing it from cambium ti.ssue in 

 general. 'I'he woody portion of the root succeeds the cambium and 

 is, as in apocynum cannabinum, made up of proscnchyma and 

 dotted ducts, iiiters])erscd with medullary rays; it is considerably 

 narrower, proportionally, than in its related species, the pith oc- 

 cupying a correspondingly larger space. None of its cells are 

 sufficiently marked, to present any distinctive points between the 

 two, that otherwise would be of value in the examination of the drugs 

 when finely ground or powdered. The pith cells are large and 

 very irregular in form and size. Bundles of elongated cells with 

 Strongly thickened walls are found in this portion of the root. The 

 starch, in this species, is exceedingly small and might easily be 

 overlooked unless highly magnified. The granules are tolerably 

 uniform in shape, being generally nearly round or oval, and are far 

 more uniform in size then in the species first described. An aver- 

 age of twenty measurements gives a mean diameter of .00498 milli- 

 meter. The largest measure was .0075 millimeter, the smallest 

 .00375 millimeter in diameter. The difference between the starch 

 granules of these two species of Apocynum are so great as to render 

 their distinction by a mere microscopical inspection an easy matter, 

 while the peculiar bast cells of Apocynum an(lro.s.xmifolium afford 

 an additional feature of value, and the pharmacist familiar with the 

 microscopic appearance of the drugs, could determine which of the 

 two was offered, at a glance. The entire operation of mounting the 

 powered drugs f)n glass slips, and making such a comparison, should 

 not exceed five minutes. Few of us are so busy that this brief 

 period cannot be spared. The method is a])iilicable to nearly all the 

 powdered drugs of vegetable origin that we use, and the results of 

 such an examination are in this class of drugs, more reliable and 

 certain than any other method affords. I may be within the limits 

 of reason in expressing the belief as well as the desire, that a micro- 

 scope will, in the near future, be regarded as essential to a phar- 

 macy as a test tube rac.k now is, and that the aliility to use it will be 

 ranked among the ordinary qualifications of the "drug clerk." — The 



