196 The Microscope. 



offshoots anteriorly, as we see on any creeping Amoeba, nor do 

 they retract offshoots posteriorly. In the direction of the forward 

 motion blunt, slightly branching and light offshoots appear sud- 

 denly, which posteriorly fade away without ever being retracted 

 into the main mass of the protoplasm. These offshoots are,, 

 therefore, nothing but protoplasm freed from basis substance 

 anteriorly, and transformed into basis substance posteriorly, thus 

 conveying the impression of locomotion. 



Strieker in his " Lectures on General and Experimental Path- 

 logy," 1883, on page 838 describes the phenomenon in the fol- 

 lowing way : " The new offshoots may have all sorts of shapes ; 

 they may be threads, knots or flaps, and spread in all directions. 

 . . . They resemble those which are pushed forward by genuine 

 migrating cells ; but in the middle of the substance of the cor- 

 nea this is only an apparent and not a real prolongation of the 

 protoplasmic body. The retraction of the offshoots is likewise 

 only apparent. If we concentrate our attention to one of the 

 offshoots, we recognize that, by becoming more transparent, 

 it gradually changes its appearance and at last fades away under 

 our very eyes, having assumed the nature of basis substance. 

 The offshoots are not retracted, but become similar to basis 

 substance and thus disappear as well defined formations. The 

 new offshoots have the same origin ; they are not pushed forward 

 from the body of the cell, but arise from the basis substance it- 

 self. The latter metamorphosis is more difficult to observe than 

 the former; but this can be accomplished the easier the more 

 active the form-changes are." 



Last year, J. H. Mennen studied the silver images of the cornea 

 both in its normal and inflamed condition in my laborator}-, and 

 has quite recently announced his concurrence in Strieker's view 

 in a paper read before the Brooklyn Medical Microscopical So- 

 ciety, September 4, 1889, and published in the Brooklyn Medical 

 Journal^ Nov. 1889. He says : " What is already seen in a lim- 

 ited degree in the normal living cornea, is in the inflamed cornea 

 a grand spectacle of a continuous change in the aggregation of 

 the tissue. Basis substance becomes protoplasm, and protoplasm 

 again basis substance, such a change taking place within a few 

 minutes. This is plainly shown in the illustration with a magni- 

 fying power of 1000 diameters, the specimen being colored with 

 nitrate of silver." 



