110 
MR. NEWPORT ON THE ORGANS OF REPRODUCTION, 
4. Evolution of the Embryo. 
The first period in the evolution of the embryo extends from the deposition of the 
egg to the gradual bursting of the shell, and exposure of the embryo within it. 
In my observations this period extended from the morning of the 6th of March, a 
few hours after the eggs had been laid, to the 31st of the same month, a period of 
twenty-five entire days. The atmosphere of the room in which the eggs remained, 
varied throughout the whole time only from about 50° to 60° Fahr. It has been 
already seen that the egg of lulus contains all the primary parts of the ovum of Verte- 
brata while still in the ovisac, and that the chief alteration the egg undergoes, after 
it has acquired a size large enough to be recognizable by the naked eye, is simply an 
increase of its whole bulk. 
I can offer but few observations on the earlier changes in the egg after impregna- 
tion, a subject already deeply investigated in other classes. I noticed, however, that 
there was considerable alteration in the appearance of the graniform cells of the yelk 
within the first day after the egg was deposited. They varied much in size towards 
the end of the day, some of them being much larger than others. The smaller ones 
were exceedingly numerous, less globular in form, more opake and granular, and 
adhered together, as if by a tenacious mucus, more firmly than in the unimpreg- 
nated egg, but I could not yet observe any trace of the embryo. The shell was still 
soft and elastic, and the egg became shrivelled and dried up if exposed to the air 
only for a few minutes. On the second day there was still no marked difference in the 
external appearance, but in the interior the whole yelk had become firmer, and the 
cells cohered more together, and I thought I could perceive some faint indications of 
the future embryo, composed entirely of large and small cells. On the third day the 
egg exhibited no further perceptible change ; but on the fourth its contents were di- 
stinctly less fluid than at any preceding period, and the cells were more globular and 
larger. This was very distinct both in regard to the larger as well as the smaller 
cells. The whole of them were more closely aggregated together, and much more 
distinct beneath the microscope. Up to this period I had not satisfactorily observed 
the outline of the embryo, but there was now a little granular mass on one side of 
the shell, which I was inclined to regard as the future being. The exterior of the 
shell had also become more firm and less elastic. Unfortunately, at this period I was 
accidentally prevented from continuing my observations, which I was unable to re- 
sume until the 25th of March, the nineteenth day after the egg was deposited. There 
was now a complete alteration in its form. It was more obtuse at both ends, and 
had become much larger. This enlargement of the impregnated egg, I have constantly 
observed in the eggs of Melolontha , Meloe and Athalia , in all of which the shell is 
elastic. At this period the outline of the embryo coiled up within the shell, and 
nearly filling the whole interior, was very distinct (Plate IV. fig. 2.). On one side 
there was a clear transparent space extending about half way across the shell, indicating 
