454 H. M. BERNARD. 



an extended account of the observations made relating to this 

 subject. Selecting one more instance, I would refer to 

 fig. 20, in which a large fluid vesicle has been discharged 

 from its associated nucleus, and apparently has not found a 

 way down as a young cone between the adjoining rod-nuclei, 

 or, if part of it has succeeded in doing so, that part did not 

 come into the optical field. Lastly, fig. 19 shows a rod 

 thrust outwards by an increase in size of its basal vacuole. 



In the second place, the staining reticulum of each rod is 

 also certainly derived from its associated nuclevis. Not only 

 can the reticulum of the inner limbs be seen in direct con- 

 nection with the liniu network of the nucleus (see figs. 29, 

 a^ i,j), but a thick stream can be seen descending from the 

 nucleus on to the ellipsoid (Hgs. 10,23, 27), a phenomenon to 

 which we shall refer more fully later on. Indeed, if the form 

 of the cone or young rod (figs. 13, d, 15, h, 23, 29, a^) with its 

 nucleus surmounting its narrow basal neck be kept in mind, 

 it is difficult to conceive of any other origin than the nucleus 

 for the large amount of staining material which finds its way 

 outwards into what was certainly originally a fluid vesicle, with, 

 at the most, a few delicate reticular strands. The longitudinal 

 fibrils running down the outer limbs are, in their shape and 

 arrangement, evidence for this outward movement, while the 

 clumps of staining matter along the whole length of their 

 threads, and the density of the reticulum in the interiors of 

 the rods, are witnesses of the immense quantity of this staining 

 matter required. 



Actual demonstration of the derivation of this reticulum 

 of the outer limb from that of the inner limb, and both from 

 the nuclear reticulum, can be seen in the figures. For in- 

 stance, there occur, in different parts of the inner limb, 

 often in the wall low down and partly apparently embedded 

 in the ellipsoid, deeply staining refractive bodies, usually 

 globular, and, what is more important to note, always sur- 

 rounded by clear zones as if they were the centres of small 

 fluid vacuoles (figs. 15, a, and 29, c — g). These are certainly 

 ' Many more are figured in Part I, PI. 3. 



