388 NOTES ON THE BREEDING HABITS 



conditions, continue to lay for many hours. A single 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 

 fertilised them. This was at the rate of forty-one eggs per minute 

 for ten hours. After the eggs are laid, the male and female sep- 

 arate, and, where formerly they remained quietly in the dishes or 

 aquaria, they now proceed to climb out, and show a tendency to 

 wander over the building. 



III.— 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 white spots with a black periphery. Sometimes 

 they are quite near to each other. Again, I have seen them sep- 

 arated by quite a wide distance. They were extruded about one 

 hour after the eggs were laid, as nearly as could be calculated. 



IV.— 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 segmenting 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 expected to find a parallel 

 case in Rana temp07'aria — that studied by Ecker, and from whom 

 the text-book 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 there- 

 fore to depart from the classical type. Rauber has given excellent 

 figures of the later stages of the frog's 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 near- 

 est the dark pole of the egg, the result being in four equal dark 

 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 light cells divides, as it were, independently of the rest. The 

 text-book figure at this sixteen-celled stage may be taken to repre- 



