HEITZMANN—FROMMANN 163 



Amoebae during life; also in that of the colourless blood 

 corpuscles of Astacus, Triton, and man, and in colostrum 

 corpuscles. With regard to the observations upon blood 

 corpuscles, I am certainly of opinion that Heitzmann, as 

 also Frommann afterwards, has partly taken post-mortem 

 appearances, of the nature of vacuolisation, for normal reti- 

 cular structures ; a proof of this is his statements concern- 

 ing the alleged differentiation or new formation of nuclei 

 in these blood corpuscles under the eye of the observer. 

 For there can be no doubt in the mind of any experienced 

 observer that this is simply a case of the nuclei becoming 

 distinct, as happens regularly after death. 



As for Amcebse, I am inclined to believe that in the 

 same way Heitzmann observed forms in which the proto- 

 plasm was thickly vacuolated, for I consider it scarcely 

 possible that he was successful in tracing out in the living 

 object the true reticular structure in the protoplasm of 

 Amoebfe with his optical apparatus. It is also very 

 apparent from Heitzmann's description that he schema- 

 tised and speculated in a most lively manner, since he 

 extended the mere indications of reticular structure seen 

 by him to the whole protoplasm. I therefore cannot but 

 ascribe a strongly hypothetical character to his work of 

 1873, which, moreover, received its punishment in not 

 obtaining the consideration it deserved. In addition to this, 

 Heitzmann forthwith expanded his observations upon the 

 reticular structure of protoplasm into a theory concerning 

 all living matter, which frequently clashed strongly with 

 the facts. His description of the origin of reticular proto- 

 plasm by vacuolisation from the so-called primitive compact 

 living matter, was altogether hypothetical, and the alleged 

 proofs were undoubtedly entirely uncertain. His efforts to 

 show that protoplasm, nucleus, nucleolus, and even inter- 

 cellular substance, were merely modifications of the one 

 living matter, and that therefore there was an easy transi- 

 tion from one to another, stood in opposition to a great 

 number of well-established experiences, quite apart from the 

 lack of any substratum of fact upon which such far- 

 reaching conclusions might be built up. Hence these 



