30 bulletin: museum of comparative zoology. 



here that Nowikoff (:05, p. 449, 450) has failed to confirm the obser- 

 vations of Hesse (:01) as to the presence of a Stiftchensaum in the 

 median eye of Branchipus. It seems to me probable that the Stift- 

 chensaum which Hesse (:01, Taf. 16, Fig. 1, a, sti.) has shown is in 

 some way a part of one of the basal plates. The general outline of 

 the area covered by the "Stiftchen" in his figure resembles closely 

 sections of the basal plates of the lateral eyes in the form I have stud- 

 ied (Plate 1, Fig. 2, la. ha.). However, all the evidence of striation 

 that I have seen is invariably distal to the margin of the plates. And 

 the latter seem to me to be as nearly homogeneous as it is possible for 

 an object to be. 



i. Relation between Neurofibrils and Interior Bodies. — It has not 

 been possible to discover, with certainty, a direct structural relation 

 between the interior bodies and the nerves, though there is a strong 

 indication that a functional relation exists between them. There is, 

 indeed, some evidence that the nerve fibres and interior bodies are 

 continuous. In the whole preparation shown in Plate 2, Figure 21, 

 there can be no doubt that the blackened structure in the opening of 

 the basal plate of the ventral eye, in the centre of the drawing, is the 

 group of nerve fibres which may be seen in many sections to leave the 

 eye at that point (cf. Plate 1. Fig. 6). In the case under consideration 

 (Fig. 21) it is very plain that there is a direct connection between the 

 nerves and one of the interior bodies, and I cannot draw the line 

 between what should be called interior body, and that which is strictly 

 nerve fibre. There can be no doubt of the fact that the two are not 

 distinct structures in the sense of their being separated from each 

 other. 



In sections, also, the indications are strongly toward a structural, 

 and therefore presumably functional, relation between nerve fibrils 

 and interior bodies. Each of the former ends distally in a club- 

 shaped enlargement (Plate 5, Fig. 49), and this is often, if not 

 always, in very close apposition to a group of interior bodies, llie 

 latter generally lie in a clear space in the cytoplasm of the cell, and it 

 is difficult to find any other structures within the space. But in Figure 

 49 in the right cell of the ventral eye (left in the figure) is shown a nerve 

 fibril (the one nearest the median plane) which, at its peripheral end 

 is divided into two twigs, each bearing a club-shaped enlargement; 

 and between the enlargements there lies an interior body. It is certain 

 in this case that the enlargements of the nerve-fibrils are within the 

 vacuole which contains the interior body. Various other, though 

 similar, conditions are shown in Figures 44, 46, and 48. In many 



