756 The American Naturalist. [August, 
copulating pair, which were laying eggs when captured, were isolated 
over night from other individuals, and in the morning a long string of 
eggs were found. Dr. E. A. Andrews carefully estimated the number 
of these, and found that inside of ten hours the female had laid the 
astonishing number of 28,000 eggs, and the male had fertilized them. 
This was at the rate of forty-one eggs per minute for ten hours. 
After the eggs are laid the male and female separate, and while 
formerly they remained quietly in the dishes or aquaria, they now 
proceed to climb out, and show a tendency to wander over the 
building. 
3. Polar Bodies.—I have seen these extruded in the egg of the tree 
frog. They are found at or near the apex of the black pole, and 
appear as two white spots with a black periphery. Sometimes they 
are quite near to each other. Again, I have seen them separated by 
quite a wide distance. They were extruded about one hour after the 
eggs were laid as nearly as could be calculated. 
4. Segmentation of the Eggs.—The series of diagrams ordinarily found 
in text-books on embryology are exceedingly diagrammatic, and give 
an entirely erroneous impression as to the appearance of the segment- 
ing egg, especially during the later stages. I found this to be the case in 
the eggs of the tree frogs (see above) and the common toad, and ex- 
pected to find a parallel case in Rana ‘temporaria,—that studied by 
Ecker, and from whom the text-bock figures are taken. During the 
present spring (’91) I have procured the early stages of segmentation 
of this frog, and found it to agree in every particular with other 
species, and therefore to depart from the text-book or classical type. 
Rauber has given excellent figures of the later stages of the frog eggs, 
and in many points I have verified his account. The first furrow 
divides the egg into two equal halves. The second at right angles to 
this gives four equal segments. The third furrow is not equatorial, but 
lies nearest the dark pole of the egg, the result being in four-equal black 
cells and four larger, but equal, light cells. At the next stage the 
marked regularity of the preceding stages is lost, and each of the eight 
cells divides, as it were, independently of the rest. The text-book figure 
at this sixteen-celled stage may be taken to represent an ideal to which 
the egg never attains. The division of the sixteen cells into thirty-two 
does not conform to any rule, although again, but in .a less degree, 
Ecker’s figures may be taken to represent in the most diagrammatic 
way possible the planes of cleavage. Without figures it is impossible 
to describe the precise method of segmentation ; those of Rauber 
approximate, I believe, most nearly to the truth. In general, we may 


