40 MONICA TAYLOR 



confined to the blocks situated normally just under the nuclear 

 membrane (PI. 2, fig. 1). The karyosome being plate-shaped 

 may appear circular (PI. 2, fig. 1) or band-shaped (PI. 2, figs. 2, 

 3). For convenience of reference these two views of the 

 karyosome will be referred to briefly as the karyosome in 

 ' plan ' and in ' elevation ' respectively. It consists of two 

 substances : (1) a ground substance which does not stain so 

 deeply as (2) another substance in the form of small blocks or 

 rods which stains like chromatin, but which, according to 

 Doflein, takes no part in the formation of the chromosomes 

 which appear on the spindle of the nucleus when it divides by 

 karyokinesis. These karyosome blocks have a more or less 

 round outline when viewed in the plan of the karyosome. 

 They appear more rod-like in the elevation view of that 

 structure (PI. 2, fig. 2). 



As the nucleus is rolled about by the endoplasm the karyo- 

 some presents not only alternate views of its plan and elevation 

 positions, but a series of positions intermediate between these 

 two extremes. Another complication now to be described gives 

 the nucleus a successive variety of appearances when it is 

 examined in the living condition. The rolling over brings 

 about a redistribution of the nuclear sap. Now the more solid 

 nuclear contents, i.e. the karyosome, the chromatin, and the 

 achromatic network, are very flexible. They easily become 

 temporarily folded. Most frequently two such folds are 

 formed from the poles towards the equator, one fold being 

 nearest the proximal surface, the other nearest the distal surface, 

 of the nucleus under examination. This has the effect of making 

 the nuclear contents appear lenticular or dumb-bell-shaped 

 (PI. 2, fig. 4). This appearance, which is exceedingly common, 

 is succeeded by the normal (PI. 2, fig. 1) as the nucleus gradually 

 steadies itself, and becomes stationary, only however to begin 

 a new series of convolutions as it is played upon by the streaming 

 endoplasm. In a well stretched, fairly young and active 

 amoeba which has got a good grip of the substratum these 

 successive changes in appearance (cf. PI. 2, figs. 6 and 7) of 

 the nuclear contents can easily be observed. In order to 



