| Show J An Egg Within an Egg t THE biological section of the museum has recently received an interesting addition from Miss Mary Christensen in the form of an egg within an egg The inner egg is about as large as a robins robin's egg that is eight or nine lines long and five lines in diameter Its shell is perfect and seems as hard as asan J Jan an ordinary egg shell In short the 1 inner egg presents all the extern external l appearances of an ordinary egg only it j f is much smaller The outer egg pre- pre all the appearances of an ordinary ordinary ordinary nary hens hen's egg The question as to how the little egg got inside of the large egg can be answered best by brief sketch of the process by which eggs are formed The egg originates in the ovary in the embryological state there are two ovaries ovaries ovaries ova ova- ries in birds as in most other animals but usually it is the left one only which develops to such an extent as to become functional The ovary communicates with the outer world through a tube called the oviduct Only the germinal cell is formed in the ovary and soon after this is is formed it passes into the oviduct through which it slowly moves towards the exterior of the body Before Before Before Be Be- fore the germinal cell has proceeded far farin farin farin in the oviduct the yolk has formed around it and immediately after the yolk has formed the white is deposited around it in layers By the time the egg is way half-way through the oviduct its yolk and white are complete and it is surrounded by the shell mem membrane brane In the extreme lower part of the oviduct oviduct oviduct ovi ovi- duct are some glands which secrete lime carbonate which is evidently deposited deposited deposited de de- posited around the egg This constitutes constitutes constitutes the shell and as soon as as' this is deposited the egg is complete and under ordinary conditions it passes from the body of the bird or is laid In the case before us an unusually small egg was formed and instead of this being being- laid it seems to have been forced up the oviduct towards the ovary In the upper part of the oviduct oviduct oviduct ovi ovi- duct it met a normal egg on its way out The full grown full grown egg forced the small egg back and in the lower part of the oviduct a shell was formed around the sized full-sized egg and the small egg which it was pushing before it thus enclosing the two in the same a shell Such cases are very rare though not wholly unknown I never heard T i i i U l of a case before where the small egg was enclosed III in a hard shell 71 C. C A. A Whiting Whiling S 'S h |
