1 68 PROTOPLASM 



say, he observed distinctly that the longitudinal fibrillse 

 were frequently connected with one another into a net- 

 work. 



As has been indicated above, as far back as 1878 I 

 expressed the opinion that the reticular structures described 

 might be alveolar, or in other words, that protoplasm has a 

 froth-like composition. 



In two memoirs of the years 18 78 and 1879 Klein 

 confirmed the net-like structure of protoplasm for very 

 many cells of Vertebrates, and declared himself in favour 

 of Frommann's and Heitzmann's views with regard to many 

 points. This was especially the case with regard to the 

 intimate connection and transition which both he and the 

 latter authors assume between the framework of the 

 nucleus and the protoplasm. Indeed he goes so far as 

 to believe, with Strieker, that fusion frequently takes 

 place between the nucleus and the protoplasm, especially 

 in the colourless blood corpuscles. The nucleus is only a 

 portion of the cell protoplasm marked off by a perforated 

 membrane. This agrees essentially, as has been said, with 

 the views developed by Heitzmann and Frommann. Although 

 I do not wish to assert that everything which Klein describes 

 and figures is really the true protoplasmic structure (which 

 is frequently very doubtful, especially in the case of gland 

 cells), yet this is the case in many of the structures 

 described. Like Eirner, he made out quite correctly the 

 fact of the longitudinal striation being only a modification 

 of the ordinary reticular structure. 



In opposition to these observations, Arnold (1879), in a 

 discussion of the investigations upon cell structures which 

 had been made up to that time, expressed himself as still 

 doubtful upon the fundamental question whether filament- 

 ous or reticular structures were present in protoplasm or 

 not ; " whether the nuclear filaments are connected with one 

 another ; whether such a relation exists between the fila- 

 ments of the body of the cell ; to what extent the reticular 

 arrangement of the filaments can be regarded as generally 

 typical ; and whether, finally, an invariable connection exists 

 between the filaments of the nucleus and those of the pro- 



