524 CRESSAVELL SHEARER AND DOROTHY JORDAN LLOYD. 
applied to reariug the pavthenogenetic plutei obtained by 
some of the vai'ious ways of bringing about the development 
of the Echinoderm egg, such as that of Loeb, Delage and 
other investigators. The following paper is a record of 
some experiments that have been carried on during the past 
two seasons at Plymouth, in an endeavour to accomplish this 
object. 
The first aim of our work was that of devising a con- 
venient method for obtaining large numbers of parthenogenetic 
plutei ; the first year, therefore, we confined our attention to 
a thorough trial of the well-established method of Loeb. 
Little success has attended the attempts of those who have 
sought to repeat Loeb’s (17) work on inducing artificial 
parthenogenesis of the eggs of the Echinoderms of our coast. 
On this account Prof. Loeb, while in England (1909), visited 
Plymouth, and made a number of experiments. He has 
handed over his data to us, with a request to determine the 
optimum times and strengths of solutions suitable to the 
peculiar conditions presented by the low alkalinity of the sea- 
water of the British coast. 
In working at Plymouth, it is first necessary to raise the 
alkalinity of the sea-water prior to the treatment of the eggs 
by hypertonic solution. 
In the second year we tried several methods, and finally 
adopted a combination of Loeb’s and Delage’s tannin and 
ammonia method. 
Our experiments have shown that parthenogenetic plutei 
obtained by Loeb’s improved method can be easily reared to 
a late stage and through metamorphosis. We have been 
unsuccessful, however, in getting the young Echini to live 
any length of time after metamorphosis, and few of our 
parthenogenetic Echini have grown to any considerable size. 
The very high percentage of larvae which we have raised 
to a late stage (twenty-five to thirty days) renders our results 
of interest. In some of our culture-jars we have had as 
many plutei go through to a late stage and form Echinus- 
rudiments, as would do so in a lot of eggs normally fertilised 
