CYTOCHEMICAL TESTS ON EMBRYOS 



339 



g. Clearing: 100^ aniline oil for 2 minutes. 



100^ toluene for 5 seconds, 

 h. Mounting: clarite. 



************ 



2. lyroaine : According to Serra (19^6) "lyrosine seems to be present in almost 

 all natural proteins in amounts which are not very different for the various 

 classes, excepting principally silk fihroin, pepsin and insulin. " The 

 formula for tyrosine is 



OOH 



HO. 



N^ 



^ 



^ 



k- 



K.' i^.p\ J 



OOCYTES OF RANA RIOIBUNOA 



Fig. 4. Tyrosine reaction, photographed wlt}iout filter. 



Fig. 5. Tyrosine reaction, photographed at higher magnification than Fig. 4 and 

 without filter. 

 *Flg. 6. Arglnlne reaction, photographed with green filter. Slight differential 



between cytoplasm, smd nucleus. 

 *Flg. 7. Same as Fig. 6 except that tlie nuclei have been separated from the cyto- 

 plasm by compression after tlie arglnlne reaction. 



Photographs hy courtesy J. A. Serra 

 ♦Figures unpublished. 



