THE FRAMEWORK AN ARTEFACT 201 



to this point I can also further adduce an observation which 

 T)r. Safftigen made in my laboratory in the summer of 1890 

 upon Epistylis <jl<'. As is well known, the ectoplasm of 

 this form, as of Vorticcllina generally, contains numerous 

 rounded, rather strongly refractile structures, which Leydig 

 once regarded as nuclei. Now the fact can be established 

 that these granules, which I regard as identical with those 

 mentioned above in Ciliata, were found at times in a state 

 of rapid proliferation by division, which of course greatly 

 supports the interpretation of them as Bacteroids. 



Since it seemed to me of importance to investigate the 

 Bacteroids discovered at an earlier date in certain animal 

 cells, with a view to their relations with the framework of the 

 protoplasm, I have carefully studied, for my own benefit, 

 Blochmann's sections through the cells of the fat body of 

 Blatta orientalis, which were filled with such bodies. It 

 was thus established that the Bacteroids, strongly stained 

 by Gram's method, lay embedded in rather a scattered manner 

 in a very pale, but distinct reticular, protoplasmic framework 

 (Plate VI. Fig. 4). Besides the Bacteroids, no granular con- 

 tents of any kind are present in the protoplasmic framework. 

 The nuclei, and more especially their chromatin granules, are 

 stained very intensely. 



As to the works of Zimmermann (1890 and 1891), 

 Mitrophanow (1889) and Luckjanow (1889), who agree 

 more or less with Altmann in their conception of proto- 

 plasm, I think I need not enter into them more specially 

 after the above discussion. 



4. Attempts to explain the Reticular Structures as Phenomena 

 of Coagulation or Precipitation 



It is really surprising that the question whether the so- 

 called structures of protoplasm are not produced by the 

 coagulation or precipitation of albuminous bodies during the 

 process of preparation, should not have been thoroughly dis- 

 cussed at an earlier period. That this was not done probably 

 depends on the fact that the investigators who worked at 

 this subject upon zoological lines were just those who, even 



