236 KrirKkwoop: POLLEN-FORMATION IN CUCURBITACEAE 
narrow spindle. The chromosomes here diverge in the anaphase 
and migrate to the poles of the spindle as two compact masses in 
which the form and relations of the chromosomes are entirely 
obscured. Only in the late telophase do the chromosomes separ- 
ate from one another and distribute themselves in the newly formed — 
nuclei (FIGURE 63). The chromatin masses soon became distrib- — 
uted along the threads of the nuclear reticulum (FIGURE 64), 
which becomes much more open and enlarged with the develop- 
ment of the spore. 
Most of the material used in this study was fixed in an acetic © 
acid-alcohol mixture, consisting of one part glacial acetic acid and ~ 
two parts 70 per cent. alcohol, which in most cases gave excellent 
results. The material was preserved in 8§ per cent. alcohol, 
cleared in xylol, and embedded in paraffine. Other methods were 
also used, particularly in the study of Micranipelis, where the pecu- 
liar cytoplasmic conditions suggested the advisability of trying 
different reagents. In this case accordingly three methods of fix- 
ation were used viz., acetic-alcohol, sublimate acetic mixture, and» 
the weaker Flemming solution. The stains employed were Haj- 
denhain’s iron haematoxylon, sections counterstained with Bis- : 
marck brown, Flemming’s  safranin- ‘oneal ~violet- orange, also 
cyanin-erythrosin and fuchsin-iodin green’ t Particula 
attention was given to the rod-like bodies in the cytoplasm oF 
each fixation. In order that conditions might be otherwise the | 
same, certain clusters of flowers of various stages of development — 
were embedded and sectioned, forming several series of ten to fif- 
teen slides, which were numbered in their proper sequence, and dif 
In the material fixed with acetic-alcohol the rod-like bod 
appeared when the preparations were stained with iron-haematoxy 
lon or with safranin-violet-orange. When fixed with sublima 
acetic (1 per cent. acetic) mixture the same cytoplasmic structu 
lon, safranin-violet-orange or cyanin-erythrosin combinations. 
material fixed with Flemming’s solution they were found only whet 
stained with the safranin-gentian-violet and orange G. The section 
were cut from 2 to 6 in thickness. 
