310 



THOS. H. MONTGOMERY, 



The preceding can be regarded as pretty good evidence from the 

 observational side for the persistence of the integrity of the chromo- 

 somes through the rest stage. More indirect evidence is contained in 

 the fact that the chromosomes come out of the rest stage in exactly 

 the same number and very much the same form as they entered into 

 it ; how could we explain this coincidence unless by assuming that the 

 integrity of the chromosomes is preserved throughout? To this whole 

 subject we shall have occasion to return in the General Part. In 

 Peripaius the chromosomes generally do not preserve their definite 

 outlines in the rest stage; but what I think is preserved, is the in- 

 tegrity of the chromosome by virtue of the continued linin connections 

 of all its granules. 



In the resting nucleus thinner linin fibrils can be distinguished as 

 well as thicker fibres; very probably the latter represent persisting 

 portions of the continuing linin spirem, i. e. axial, central or distal 

 fibres. 



The volume of the resting nucleus varies; and its form, while 

 generally spherical, is more or less dependent upon the form of the 

 cell body, and the latter upon the pressure of the surrounding cells. 

 Unlike the case in the spermatogonia, the nuclear sap does not stain. 

 The nuclear membrane reaches its greatest thickness at this stage. 

 Nucleoli {n Figs. 100, 104 — 107, 109) of comparatively small size 

 occur to the number of one to three (usually two) to a nucleus, are 

 always peripheral in position, usually spherical, and without vacuoles. 

 In the spermatogonia the amount of nucleolar substance is relatively 

 much greater, and the number and form of the nucleoli much more 

 variable, but the staining reactions in both generations of cells is the 

 same. I was puzzled at first by their staining reactions, which are 

 somewhat unlike those of the sperm cells in Pentatoma. The contrast 

 is shown in the following table: 



Stain 



Pentatoma 



true nucleolus chromatin nucleolus 



Peripatus 



Iron haematoxyline 

 Hermann's stain 

 Ehrlich- Biondi 

 Haematoxyline-eosin 



deep black 



red 



red 



red 



brown 

 unstained 

 red 

 red 



deep black 

 red 

 green 

 blue 



Now one of my main reasons for undertaking the present study 

 of the spermatogenesis of Peripatus, was to find whether this form, 



