408 



University of California . 



[Vol. 3, 



pact limestone matrix conceivable. It could hardly have passed 

 through the capsule dissolved in some light solvent and have 

 been distributed inside the shell in the various positions in which 

 it is at present found. The possibility of its having entered in a 

 gaseous state is prohibited by its ready decomposition when 

 heated. Furthermore, had it come in from outside there should 

 be traces of it in the surrounding capsule. Analysis of the 

 matrix has shown no tar or other carbonaceous material likely to 

 produce it removed any distance from the egg. That present 

 outside the shell can be accounted for most easily by the assump- 

 tion that it has been forced out from the interior. 



The great improbability that the tar is of external origin is 

 thus clearly indicated. On the other hand the probability that 

 it has been derived from the material originally present in the 

 egg is suggested indirectly by the quantity of bituminous matter 

 estimated to be present in this fossil. Its carbon content is such 

 that it might readily have been derived from the organic matter 

 present in an egg of this size after due allowance has been made 

 for the production and subsequent disappearance of the necessary 

 amounts of ammonia, water, and carbon dioxide. A consider- 

 able quantity of methane might have been lost as well. The 

 absence of nitrogen does not argue against this origin, but rather 

 strengthens such a hypothesis, since from bis attempts at 

 artificial synthesis Engler was led to the conclusion that the 

 bituminizing process has to do not so much with protein as with 

 fat. From the amount of fat present in a duck's egg of the size 

 of this specimen, all the tar might have been derived even if the 

 proteid matter had entirely disappeared in the form of the ordi- 

 nary products of decomposition. The chemical character of the 

 original egg content could not have differed materially from that 

 of eggs of existing birds, and in the necessary decomposition 

 and concentration all existing eggs would give a product of 

 practically the same composition. 



While absolute proof cannot be given, the evidence amounts 

 almost to a demonstration that the bituminous substance now 

 present in the egg represents a part of its original organic con- 

 tents. In the absence of any evidence to the contrary we may 

 accept that origin toward which all the evidence points. This 



