350 CEESSAVELI; SHEAKEE, WALTEE DE JIOEGAN, H. M. FUCHS. 
tliut the sperm chromatin h:is not necessarily any influence 
on the structure of tlie hybrid. Other investigators in 
hlchinoderm liybridisation who have found a purely maternal 
inheritance (Driesch (5) and Hagedoorn (7) ) have not 
investigated the cytology of their crosses. In order to decide 
whetlier or not there was a true fertilisation in our experiments 
w'e handed over hybrid eggs fixed in the early segmentation 
stages to Doncaster and Gray. A preliminary account of the 
results of their investigation was publislied last autumn (4). 
At that date they had onl}’ examined one- cross into which E. 
miliaris entered, namely E. acutus 2 x E. miliaris S. 
In these hybrids there was a true fusion of the male and 
female pronuclei, so that this seemed to be a case parallel with 
that of Godlewski. 
Baltzer (1), working at Naples in 1908, found that in his 
crosses, although there was a true fusion of the pronuclei, a 
varying number of chromosomes were thrown out in the early 
segmentation divisions. He also claimed that chromatin was 
eliminated as late as the blastula stage. Tennant (13) has 
has also found elimination of chromosomes in the early stages. 
It is possible that such a rejection of chromatin may take 
place at an early or a late stage in our Echinus crosses, and 
that sometimes paternal chromatin may be thrown out while 
at others maternal. A change in elimination of this nature 
might be correlated with the change in inheritance which we 
have desci-ibed above. 
A full account of the investigation of Doncaster and Gray, 
which was made on identical material from which some of 
our crosses were raised, will appear shortly in this journal. 
During this summer we have investigated the inheritance 
of characters in the young hybrid sea-urchins after metamor- 
phosis. An account of this work will be given in a late)’ 
])aper. A method has been fouiid of feeding and raising the 
ui’chins in the laboratoiy and a number of these have now 
reach a considerable size. It is hoped that we may obtain 
fi-om thein a second g’eneration. 
