2 PROTOPLASM 



this time through the works of Frommann, Kupffer, Heitz- 

 niann, and others. I remarked at that time that the facts 

 which had become known concerning this point " do not, 

 however, seem to me by any means so noteworthy and so 

 unconnected with former observations as was usually repre- 

 sented. From the protoplasm of many Protozoa in which 

 appear single scattered vacuoles there is a gradual transi- 

 tion to be found to completely alveolar or, what is the 

 same thing, reticular protoplasm, where the alveoli are so 

 densely crowded that their real protoplasmic walls take on 

 a honeycombed arrangement, which in optical section appears 

 reticular." I further remarked that in the hyaline cortical 

 layer and the pseudopodia of Ehizopods, we had before us 

 structureless homogeneous protoplasm. Thus, as far back as 

 1878, I represented the view that the reticular structure of 

 protoplasm described by various investigators was a honey- 

 combed or alveolar structure. 



My extensive dealings with Protozoa of very various 

 groups, to which I had to devote myself during the follow- 

 ing years, gave me the opportunity for many an observation 

 upon protoplasmic structures, which more and more con- 

 firmed me in the view I had already expressed in 1878. 

 In the years 1884 and 18851 was first able to study more 

 thoroughly relations of this kind in 1884 Noctiluca ; in 

 1885, a series of marine Bliizopods, Adinospliccrium, and 

 certain Ciliata. More definitely than before I expressed 

 my conviction that the so-called reticular structures should 

 be interpreted as honeycombed, and founded this conception 

 upon the proof of the indubitable honeycomb structure of 

 the so-called " alveolar layer." I also brought forward 

 proofs of the reality of the protoplasmic structures, the 

 resemblance of which to the products of the coagulation 

 and precipitation of various substances might awaken a per- 

 fectly justifiable suspicion as to whether they did not also 

 belong to the same category of phenomena. I soon found 

 occasion for engaging still more thoroughly in studies of this 

 kind, when in the years 1886-88 I undertook to do the 

 Ciliata for Bronn's Klassen und Ordnungen. In my own 

 studies upon this group I was able to avail myself of the 



