Protoplasmic Structure 43 



It might appear from diagrammatic illustra- 

 tions on paper that when a spirazine folds over 

 upon itself, the amino and carbonyl groups of the 

 folded over portion would come directly opposite 

 the carbonyl and amino groups, respectively, of 

 the remaining portion, so that they would be likely 

 to combine chemically as suggested in Fig. 4. It 

 is doubtful, however, whether such a double union 

 occurs in nature. The adjacent portions of the 

 convolutions of two spirazines with the same di- 

 rection of twist will always slope in opposite direc- 

 tions, which may render it difficult to bring the 

 amino and carbonyl groups directly opposite each 

 other along two different lines without consider- 

 able distortion of the spirazines themselves. Fur- 

 thermore, the structure thus produced would con- 

 stitute merely a flat sheet containing only a single 

 layer of spirazines which would be incapable of 

 forming three-dimensional structures. 



It seems more likely that the folded-over por- 

 tion will join the remaining portion along only a 

 single line, so that a repetition of this process will 

 produce the triplet shown in Fig. 5, and a con- 

 tinuation of the same process over a large area 

 will produce the configuration of polygonal com- 

 partments shown in Fig. 6. 



A group of three spirazines connected as shown 

 in Fig. 5 may have constituted the most primitive 



