466 
,T. GRAY. 
IV. Summary of Experimental 'Work. 
(1) The chromatin of Echinus acutus under certain 
abnmoral conditions behave differently to that of E. escu- 
lent us which is subjected to similar conditions. 
(2) 'f’he effect of hypertonic solutions of a certain strength 
on the fertilised eggs of E . ac utns is to cause the elimination 
of chromosomes from the nuclei by a pi’ocess exactly similar 
to that which is normally found in the hybrid eggs of the 
cross E. esculentus c? x E. acutus ?. This phenomenon 
cannot be induced in the fertilised eggs of E. esculentus 
by similar treatment. 
(3) In eggs of which the whole nuclear structure has been 
disorganised, the first segmentation division is normal. 
(4) The later segmentation of all eggs which have been 
treated with hypertonic solutions is abnormal. 
V. Comparison of Results with those of other 
Investigators. 
In 1903 Teichmann (17) published an account of the cyto- 
logy of the eggs of Echinus microtuberculatus fertilised 
by the sperm of the same species, which had been treated 
with ‘05 per cent, solution of strychnine previous to use. He 
showed that the male chromatin failed to become active until 
after the first segmentation division, during which period it 
can be seen lying near to the spindle as a compact chromatic 
body. Later on it becomes active and amalgamates itself 
with the female chromatin of one of the blastomeres. 
In 1911 Konopacki (7) described the effect of hypertonic 
solutions upon the fertilised eggs of Strougylocentrotus 
lividus and Echinus microtuberculatus. Although a 
detailed description of the chromatin is not given, it may be 
concluded from his figures that his results were similar to those 
described iu this paper for Echinus esculentus and E. 
acutus. Figs. 1, 2 of Konopacki’s work show irregular ana- 
phases in Echinus eggs which have been treated for half an 
