6 HEPORT ON THE SPAWNING OF THE COMMON SOLE. 



towards the surface from within an inch or two of the ground, and 

 fresh eggs taking their place to the accompaniment of the movements 

 described, would draw the conclusions that I have. 



In considering how it is that the fish come to the front of 

 the tank, and will spawn undisturbed while you are just on the other 

 side of the glass, instead of, as one might have expected, retreating 

 to the farther side, one must remember that the fish now 

 spawning have been five years or so in the aquarium, and that 

 thus they are not only more or less tame generally, but have 

 probably come to consider the window border of the tank 

 floor as their place of assembly 'par excellence ; for it is to that side 

 that they are impelled by the common craving of hunger as feeding 

 time approaches, and on that side that they at all sorts of times tend to 

 linger, from that milder motive of curiosity about us strange creatures 

 in the air-tank on the other side of the glass. 



V. General Eemarks on the Development. 



On the three occasions on which I tried, I failed to obtain eggs 

 from the living fish, and thus I never witnessed the process of 

 fertilization so as to time the development from the very beginning, 

 as I should have liked. Perhaps I should have succeeded, had I 

 captured the fish as soon as they began to spawn. However, I obtained 

 eggs one hour before the first formation of the protoplasmic disc at the 

 lower side of the egg, and two and a half hours before the first 

 segmentation. 



The rapid streaming of the protoplasm between the large yolk 

 spheres of the lower part of the egg (which spheres became temporarily 

 transformed into cones pointing downwards), to form the disc, was 

 a very interesting sight. What I saw fully bears out the late George 

 Brook's explanation* of Kuppfer's account of the phenomenon in the 

 herrinff's e<fg. 



Segmentation was repeatedly followed and sketched, such sketches 

 agreeing essentially as to direction of the segmentation furrows with 

 Wilson's figures of the segmentation stages of the sea bass ; but I saw 

 no nuclei in the living egg, except in the " parablast " at a much 

 later stage. 



The intervals between the segmentations decreased markedly at first, 

 but a limit was soon reached. The rate of development, of course, 

 varies considerably with the temperature of the water, whether one 

 considers particular stages, or the whole time before hatching, 



• G, Brook, "The Formation of the Germinal Layers in Tcleostci," Trans. Boy. Soc. of 

 Edinbitrijh, vol. xxxiii. part i. (for 1885-0), publ. 1887. 



