DEVELOPMENT OF EGGS OF ARBACIA AND CILETOPTERUS. 28l 



Twenty-four hours after the experiment began, ciliated larva- 

 were present in great numbers in all of tin- solutions, but they 

 all died many hours before tin- death of tin- lar\a- in the control 

 culture. 



Glycocott (C 2 H,\< >. . This -ub-tance, which is the' -implest 

 of the amido-acids, was much 1< h.irmful to the < ggs of Arbucia 

 than wen- .my of the- other amido-.u id- n-ed in the-e experiment-. 

 During the first twenty-four hour- the development of tin- eggs 

 did not appear to be affected in any wa\ by the -..Union- u-ed 

 Ci, .], -I-Q and ;jV per cent .), but during the second day the emlir\ is 

 began to show degenerative change-, ,md all of them died about 

 fifty hours after the experiment be^.m. Sections <if the-e eggs 

 fixed at various stages of de\elopment merely continued tin- 

 observations on the living forms, as no unu-ual t\p<- of lar\a- 

 were found. 



Alanin (CsHyNOO. This amido-acid di--ol\e- re.idiK in cold 

 sea-water, and it was used in solutions of tin- toll<i\\in- -in-n-th-: 

 2, i, .], -j 1 ^ and u'fl- per cent. The stn-n-cr -oluiimi- 2, i and 

 .1 per cent.) retarded development from the l.e-imiin- : tin- 

 weaker solutions had no apparent elicit- on the -e^mentarion 

 ot the eggs. After twenty-four hours each of the -olntioii- con- 

 tained a large number of swimming lar\.e. and onl\ iho-e in the 

 j l>er cent, solution showed any e\ i<K IK e n| reiaided de\elop- 

 n lent. The embryos in all of the culture- died -c.me hour- bet- >ie 

 the death of the control larva', so weak i-olution- ,,f .ilaniii cannot 

 be considered as favorable media in \\hich to rear the eggs of 

 Arhiititi. Preserved material -houed no .ilniorni.ilitie- \\orthy 

 oi note at an\- stage of development. 



All of the amido-acids used in tin- series of experiment- with 

 the eggs of Arbacia proved to be toxic, the injuriou- effects of 

 anv -ub-tance depending \t_-r\- lar^t-K upon the -tren-th of the 

 solution u-ed. In no case was the cour-e of development altered 

 in a definite direction, except in tin- very young eggs and in these 

 the % ib normalities produced were of the types commonly found 

 when fertilized eggs of the -e.i-nrchin are treated with various 

 cheinie.il -olutions. 



