PA.TERNAL CHARACTERS IN ECHINOID HYBRIDS. 337 
On Paternal Characters in Echinoid Hybrids. 
By 
C^rcsswell Sliearei', Walter De ItIoi-g:an, and H. HI. Fuchs 
With Plates 17 and 18 and 4 Text-figm’es. 
(From the Laboratory of the Marine Biological Association, 
Plymouth). 
I. Introduction. 
Last autumn we published a paper (12) giving a brief 
summary up to date of some tliree yeaiV work on the hybridisa- 
tion of Echiiioderms. The experiments were made with the 
tliree species of Echinus found atPlymoutli. From a study 
of tlie late larval characters of the pure forms and of the 
liybrids we arrived at the conclusion that the inheritance of 
these characters was invariably maternal — that is to say, that 
the late larval hybrid always resembles its mother. Since the 
date of the publication of our preliminary paper we have 
continued our experiments, and have had occasion to repeat 
all our crosses. TV our surprise, however, the behaviour of 
some of the hybrids has differed greatly this season from that 
of previous years. In late lar ml life some of the hybi-id 
crosses have shown as strictly a paternal inheritance as in 
previous years they showed a maternal one. It may therefore 
be of interest to other investigators in this field of work if we 
publish a short account of these new facts before the comple- 
tion of our full paper. 
In our preliminary paper we have clearly pointed out that 
the very conflicting results which have been obtained by 
different investigators in Echinoderm hybridisation are in 
large part due to the study of insufficiently definite characters. 
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