2 Mr Gray, The Efect of Hypertonic Solutions 
become separated tend to take up positions round the edge of the 
equatorial plate, sometimes outside the spindle. The normal 
chromosomes, and those of which the normal shape has not 
become much altered by vesicle-production, then split longi- 
tudinally in the ordinary way, and begin to travel to the poles. 
It may sometimes be seen that a chromosome with a vesicle 
attached has split, and the vesicle, remaining attached to one half, 
is being carried with it towards the pole. It is possible that a 
few chromosomes, the greater part of which has become swollen 
into a vesicle, do not divide, but are carried entire to one or 
other pole. The vesicles which have become separated from their 
parent chromosomes appear to differ in their fate according to 
their position. If they le among the chromosomes inside the 
spindle, they are carried with them to one or other pole and 
become included in the daughter nuclei. If, however, they are 
left on the edge of the spindle, as commonly happens with the 
larger vesicles, they remain outside the mitotic figure in the cyto- 
plasm, and are not included in the nuclei of the daughter cells. 
In this case they usually contract and become small evenly stained 
spheres, not easily distinguishable from the larger yolk-granules, 
but usually recognisable after the cell-division is completed, lying 
in the cytoplasm near the boundary between the two cells. 
In the second segmentation division, a similar process takes 
place, but is usually rather less pronounced; the vesicles are on 
the whole -smaller, and we doubt whether complete chromosomes 
ever become vesicular *.” 
A similar phenemenon within the eggs of Echinoderms has 
recently been described by Konopacki. He treated the fertilised 
eges of Strongylocentrotus lividus with hypertonic solutions of 
certain strengths for half an hour, and subsequently transferred 
to sea-water. Although no detailed description is given of the 
behaviour of the chromatin, a study of his figures leads to the 
conclusion that the effect of such solutions upon the fertilised 
eges of Hchinus esculentus and EL. acutus would throw some hght 
upon the cytology of hybrids derived from these species. ‘The 
following are the chief results of such experiments carried out 
this year at Plymouth. 
Eggs of H. esculentus were fertilised and allowed to remain 
in fresh sea-water for one hour: they were then transferred to 
a mixture of 50 cc. sea-water + 6 cc. 24 M.NaCl solution, and 
after half an hour were transferred to fresh sea-water until the 
first mitotic figure had been formed. 
The eggs were then preserved and sectioned: the stain used 
being Heidenhain’s Haematoxylin. Such preparations shewed 
that the most interesting effect of the hypertonic solution was to 
* Proc. Camb. Phil, Soc. Vol. xvi, Pt. v. 1911, p. 415. Doncaster and Gray. 
