DR. W. H. RANSOM ON THE OVUM OF OSSEOUS FISHES. 
499 
Fig. 
34. 
Fig. 
35. 
Fig. 
35'. 
Fig. 
36. 
Fig. 
37. 
Fig. 
38. 
Fig. 
39. 
Fig. 
40. 
Figs 
. 41 
Figs. 
43 
Figs. 
45 
Figs. 
, 50 
Figs. 
, 52 
Fig. 
54. 
Fig. 
55. 
Fig. 
56. 
Fig. 
57. 
Fig. 
58. 
Fig. 
59. 
Fig. 
60. 
Fig. 
61. 
Fig. 
62. 
The figures 34 to 83 inclusive refer to the eggs of Gasterosteus. 
Two ova of Gasterosteus pungitms, pressed together so as to seem to close the 
micropyle of one of them. X 100. 
An impregnated ovum of G. leiurus, just before the commencement of vivid 
contractions, showing the flat surface. 
The same egg rolled a little. 
The first stage of active contraction producing the reniform figure. 
The dumb-bell figure. 
The flask-shaped figure. 
The wave having passed forwards, has left the food-yelk globular, but still in- 
fluences the germinal disk, which is nipple-shaped. 
The whole yelk-ball globular and at rest. The germinal disk diffused somewhat. 
& 42. Abnormal forms of the yelk, caused by two or more waves present at the 
same time. 
PLATE XVII. 
& 44. Slower changes of form of the germinal disk and neighbouring part of the 
food-yelk. 
to 49 inclusive. Further successive slow changes in the form of the germinal 
disk and of the germinal surface of the food-yelk, shortly before the commence- 
ment of cleavage. 
& 51. Show the commencement and progress of the first cleft, and the sepa- 
ration of the masses. 
& 53. Also show the gradual deepening of the first cleft. 
The cleavage masses closely pressed together as seen before the second cleft 
begins. 
Shows the “ Faltenkranz ” of Reichekt, or folds of the inner sac during the 
progress of the first cleft. 
Shows similar folds in one cleft of an egg which is cleaving irregularly. 
An egg twenty hours after impregnation. The germinal mass is composed of 
cell-like corpuscles ; b, a portion of the germinal mass more highly magnified. 
An egg cleaving asymmetrically. 
The yelk-ball before galvanism was used (given as a standard of comparison) : — 
a, the micropyle ; b, the germinal disk. 
Contraction, the effect of one application of the galvanic current. 
P. The Platinode. Z. The Zincode. 
Another contraction, the effect of a second application of the current, with 
rupture of the inner sac and escape of the food-yelk. 
Further contraction, with rupture of the inner sac on the opposite side, from a 
third application of the current. The escaping yelk granular. 
