356 IMMUNOLOGICAL STUDIES 



An example of a specific effect with an antiserum against a 

 highly purified antigen is contained in the work of Ebert ( 1955 ) . 

 Antisera against cardiac actin when administered in ovo to chick 

 embryos at 48 to 60 hours blocked further development of the 

 heart and resulted in death of the embryo. With appropriately 

 diluted antisera against saline extracts of adult chicken heart, 

 brain, and spleen Ebert ( 1950 ) had earlier reported specific in- 

 hibitory effects on the development of the homologous organ. The 

 more concentrated antisera gave nonspecific lethal and growth- 

 inhibitory effects even after absorption with heterologous organ 

 extracts. Johnson and Leone (1955) report that anti-actomyosin 

 inhibits morphogenesis of the heart in chick embryos, but the de- 

 gree of specificity is not clear since there is also general inhibi- 

 tion of development. Antisera against lens protein have also been 

 reported to produce specific lens damage in 6- to 8-day chick em- 

 bryos ( Burke et ah, , 1944 ) . Experiments with antisera against 

 saline extracts of amphibian embryos by Flickinger and Nace 

 ( 1952 ) and by Clayton ( 1953 ) have given some indication of 

 stage-specific inhibitory action, but the authors consider further 

 tests necessary to establish the selectivity of the action. Nettle- 

 ship (1953) reported that antisera against chicken whole embryo 

 brei, when injected into the incubating egg, blocked development 

 at the corresponding stage. For an un absorbed antiserum of this 

 type to produce a highly specific effect does seem surprising, and 

 one wonders whether or not this might be due to fortuitous varia- 

 tion in the antibody content of the various antisera. 



The experiments cited point to possible uses of antisera in mod- 

 ifying development in specific ways. As yet, however, they have 

 been too limited in scope to provide information that can be used 

 for further analysis of problems of induction and determination 

 in early development. 



Inhibition of Cleavage in Sea Urchins 

 by Specific Antisera 



The author has for many years prepared antisera against vari- 

 ous constituents of the spemi, eggs, developing embryos, and 

 adult tissues of sea urchins as part of a program of investigation 



