﻿136 



William S. Marshall and Paul H. Dernehl, 



limited by the ainount of it which extends beyond the margin of 

 the archoplasm. Those astral fibres lying nearest the spindle fibres 

 are the longest, often extending so far that they meet similar fibres 

 from the other pole. Just outside of the spindle fibres a clear space 

 was sometimes noticed, widest at the equatorial plate and from here 

 narrowing towards the poles (Figs. 13 and 15). Its general appearance 

 was as if the cytoplasm lying nearest the connecting fibres was 

 shrunken and pulled away from them. 



In many eggs in which dividing nuclei were abundant nearly 

 all stages of mitosis could be found within a Single egg. A stage 

 in which the ehromosomes have left the equatorial plate and started 

 towards the poles is seen in Fig. 14. Excepting the slight divergenee 

 of the ehromosomes towards the poles, the figure is similar to the 

 one just described. The ehromosomes are quite distinet, centrosomes, 

 archoplasm and astral fibres present, the spindle fibres slightly 

 shortened. Connecting fibres are not yet visible; they appear at a 

 little later stage (Fig. 23) and remain distinet until the daughter 

 nuclei begin to form. This last figure mentioned is the earliest we 

 could find in which connecting fibres were present. After the arrival 

 of the ehromosomes at the poles they still remain distinet from each 

 other (Figs. 17 and 20); in some speeimens they apparently group 

 closer together than in others and do not then remain distinet but 

 overlap and appear like a Single, irregulär, darkly stained mass 

 (Fig. 18). Each group of ehromosomes now lies near the archoplasm 

 which is still present, showing, as earlier, a distinet radiation. The 

 centrosomes, as easily seen as during the earlier stages, are still 

 present near the center of the archoplasm. 



From their first appearance the connecting fibres are in all 

 dividing nuclei very distinet, remaining so until the two nuclei 

 resultant from the division have been formed. We observed in 

 Polistes that the connecting fibres often appeared peculiar in that a 

 number of irregulär thickenings occurred on them, appearing without 

 any regularity as to position or number (Figs. 17 and 19). Generally 

 rnore than one swelling was present on a fibre, and, if so, they 

 might be near together or far apart. In one instance they were 

 observed directly in the equator (Fig. 18), but were smaller than 

 usually seen, and only two present. Somewhat similar struetures 

 are those found by Hoffmann (26 a) in the Hydroids but were always 

 along or near the equator, and do not occur so early in mitosis as 

 we found them in Polistes. Carnoy (12) has figured similar thickenings 



