84 OTTO GLASER. 



The test which is sensitive roughly to i part in 50 million, is not 

 vitiated by the presence of sea-salts nor by small amounts of iron, 

 lead, nickel, cobalt, zinc, or manganese. Results : Positive and very 

 decided. 



5. Copper as Crystalline Cupric Sulplvate — CuS0 4 -5H 2 0. 



After precipitation of the iron as hydroxide the ash was redissolved 

 in sulphuric acid and drops of the solution allowed to evaporate to 

 dryness on a slide. Under the microscope long blue needles corre- 

 sponding to copper sulphate. The blue color greatly intensified by 

 ammonia. 



6. Copper as Metallic Copper- — Cu. 



5 c c. of A plus excess NH 4 OH. Copper if present in sufficient 

 quantity should be deposited on tin-foil. Result : positive but faint. 

 With aluminum, however, despite incompleteness, the deposition was 

 very marked ; film, rose-colored by reflected light ; bright and typically 

 copper-colored when polished. 



7. Copper by Electrolytic Deposition. 



10 c.c. of A. Platinum Electrodes. Voltage 2.6; amperage 1/10. 

 At this tension copper and only copper can be deposited on the kathode. 

 After 24 hours, result positive and distinct. Could not be weighed. 

 Redissolved deposit and got positive test with. potassium ethyl xanthate. 



On the basis of this evidence it was no longer possible to doubt 

 the existence of copper in the normal Arbacia egg. The basic 

 necessity for a secretion of copper compounds or copper-bearing 

 substances is therefore given. If such materials are held up tem- 

 porarily by the chorion, the differences between normal and de- 

 chorionized ova, noted in sections IV. and V., would be explained. 

 But do the eggs really secrete copper in any form? We could 

 perhaps answer this question if we could associate the metal with 

 definite structures and substances in the egg. 



VII. Localization of Copper in the Arbacia Egg. 

 The problem calls for the localization of the copper. I em- 

 ployed direct methods as well as indirect. The eggs used were 

 shed under the conditions previously mentioned and fixed in abso- 

 lute alcohol. I studied both whole mounts and sections, 5/* in 

 thickness. The latter, after removal of the paraffin, like the un- 

 sectioned eggs, were treated with various reagents and examined 

 in the opaque condition, wet or dry; or after clearing, as trans- 

 parent objects, in glycerine or balsam. All the reagents were 

 tested and again found negative for copper. 



