esterly: eucalanus. 17 



(Fig. 1). The only^ question connected with their occurrence is 

 whether or not that is their normal form. There can be no doubt that 

 the rod-hke forms are not optical sections or isolated portions of 

 band-shaped bodies which have been so crumpled or folded as to be 

 cut into many scattered bits. There is the possibility, though I be- 

 lieve it is remote, that both rod-like and band-like interior bodies 

 occur in the retinal cells. 



The cpiestion as to the branching of the interior bodies, which was 

 raised by Hesse, is a debatable one. My belief is that branching does 

 not occur, though in some preparations it appears to (Plate 1, Fig. 5). 

 Here, again, it seems probable that the branched appearance is due 

 to the fact that numbers of rod-like bodies are closelv massed too;ether. 

 the apparent branching being in reality due to the protrusion of the 

 ends of certain spicules or groups of spicules from the more general 

 aggregation of them. Indeed, the appearance of a branching habit 

 seems to me to be strong evidence that the band-form of the interior 

 body is really not the unit of structure in cases where it occurs, for 

 often (Plate 1, Fig. 8) an end of an otherwise apjiarently homogeneous 

 ribbon is frayed out. I am at a loss to account for this frayed or tas- 

 seled structure except on the assumption that masses or groups of rods 

 or spicules compose the ribbon. 



The interior bodies stain in the same M^ay that the nuclei do. This 

 holds for all of the staining methods I have employed. The colora- 

 tion is the same in the two objects in either iron-haematoxylin, Ehrlich's 

 haematoxylin or acid haemalum. Vom Rath's fluid blackens or 

 browns all the structures in the cell, — plasma, nucleus, and interior 

 bodies, alike. But iNIallorv's connective-tissue stain is especially good 

 for differential staining. \Mien sections are treated in this way, 

 the nuclei and interior bodies become yellow, all other structures red 

 or reddish-purple, except chitin and connective tissue, which become 

 blue. The interior bodies are evidently highly differentiated portions 

 of the cell, though there is no reason to think that they are in any way 

 the equivalents of nuclear structures, since their appearance in rather 

 heavily stained haematoxylin preparations is vitreous and refractive. 

 This is true to some extent, also, in INIallory's stain, and is especially 

 evident if a vom Rath preparation is well decolorized in hydrogen 

 jieroxide. The interior bodies are ordinarily as deeply stained as any 

 other part of the retinal cells, but they decolorize more quickly and 

 then appear as refractive or colorless objects in the brown cytoplasm. 



It is difficult to describe the interior bodies in general terms. The 

 isolated ones are rod-like or spindle-shaped, and this is in general the 



