The Miceoscope. 107 



which have equal diameters in their mature form and which color 

 diffusely, and to call these ovoid organisms bacteria, where the 

 longitudinal diameter does not more than over again exceed the 

 transverse. As to bacilli, spirrilli, etc., there need be no dispute so 

 plain are their morpho-characteristics. 



The mature micro-etiological oi'ganisms of the American swine 

 plague and southern cattle plague has been described above (fig. 1) 

 as resembling a white bean with the ends painted, as well as its 

 sides, leaving the middle portion of its body unpainted, as we look 

 down upon it. Now, that is the picture which the eye generally 

 receives, but a more exact inspection of a stained covering-glass 

 specimen will show that the above is not always the appearance pre- 

 sented to the eye, even by the mature germ. The above description 

 depends upon the germ presenting itself to the eye in an exact hori- 

 zontal position : that is, lying straight on its horizontal axis. If, 

 however, it be turned a little one way or the other on its horizontal 

 axis, numerous specimens will be seen where the white belt does not 

 extend entirely across the object, as above described, but seems to 

 be limited more or less to one side, and more of the colored sub- 

 stance will be seen on the opposite side than under general circum- 

 stances, or perhaps better in exact inspection (tig. 1|). At first I 

 mistook the appearance for the accumulation of the uncolored sub- 

 stance in this way during the process of its secretion from the 

 colored ends, which I take to be the method by which this non- 

 coloring material is produced. I believe that one of the best ways 

 to instruct others is to chronicle our errors and explain them. 

 Hence, I have done so in the preparation of this manuscript. More 

 mature reflection has shown me that the above explanation is partially 

 or wholly incorrect. It has been mentioned that that portion of the 

 capsule of these micro-organisms must have the same chemical com- 

 position as the pole ends, because it also colors somewhat under the 

 same application of the tinction. Now, why does it not show the same 

 intensity of coloring ? The only answer is : that this capsule, being 

 very thin, cannot take up as much color as the more dense pole ends ; 

 and being so thin, by the same amount of exposure, does not show 

 any color ivhen the middle of the object is looked directly doivn 

 upon, but ivhen the eye strikes the sides of the object, then we look 

 through more material, and hence see more color. Just as when we 

 look at a piece of window glass, or a good glass slide, if we look 

 directly through it it is colorless, but if we turn it on edge and look 

 at it, it has a more or less green shade, according to the quality of 



