CHROMOSOMES OF MOSQUITO 531 



The double thread terminating in the granules has become very 

 much condensed near them. It is of interest to see that there 

 are four threads connected with the nucleolus and that at least 

 one of them may be continuous between the nucleolus and the 

 terminal granules. Figure 38 represents a later stage in which 

 the four single threads connected with the nucleolus have fused 

 into two double threads. 



In figure 39 the still diffuse chromosomes appear distinctly 

 as three pairs, the smaller pair at the center of the figure and 

 at a much lower focus than either of the others. The two larger 

 pairs are at the sides with the members united at the ends. The 

 pair at the right shows the terminal granules. The nucleolus 

 is still very black and is at considerable distance from the pair 

 at the right, but connected with the middle of the same by an 

 achromatic fiber. 



Figures 40 to 47 are from sections which have been very much 

 overstained in order to bring out the more diffuse elements. In 

 consequence the chromosomes are very black and the members 

 of each of the three pairs appear more or less fused. 



Figure 40 shows one of the larger pairs with the diffuse nu- 

 cleolus attached to its middle and the terminal granules each 

 appearing double. The more distal parts of the latter are very 

 black. In figure 41 the terminal granules are rather large; the 

 attachment of the nucleolus can not be made out. Figures 42 a 

 and 42 b show a nucleus cut in sectioning. The terminal gran- 

 ules are here very small. The nucleolus, now appearing double, 

 is connected with the large pair of chromosomes which bear 

 the terminal granules. The two other pairs have been broken 

 in the middle, the point of spindle-fiber attachment. Figure 43 

 shows the diffuse nucleolus and a terminal granule attached to 

 the same large pair. The other terminal granule could not be 

 seen but is probably hidden under the chromosomes. In figure 

 44 the nucleolus has become exceedingly diffuse and in figures 

 45, 46, and 47 is not visible. The terminal granules vary greatly 

 in size, in 47 becoming hardly more than faint threads. 



2. Later prophases to early anaphases. Tetrads. In order to 

 make clear the conditions shown in the succeeding figures of 



