368 M. M. Mercatr 
Fig. 170. A copulating pair from a tadpole of Bombinator pachypus, infected 
88 hours. 
Fig. 171. A copulating pair from a tadpole of Bufo vulgaris, infected 45 hours. 
The microgamete was the smallest I have seen of this species. Its nucleus was 
not visible. Drawn from life. 
Fig. 172. A copulating pair from a tadpole of Bufo vulgaris, infected 60 hours. 
Acetic-carmine. Magnification not recorded. 
Fig. 173. A copulating pair from a tadpole of Bombinator pachypus, infected 
7 days. The macrogamete is much larger than usual. Acetic acid. > 673 diameters. 
Figs. 174—177. Successive stages of copulation, drawn trom life: Fig. 174 
at 12% POM. Bic. 175 at, 12° oP. Mes io 1 7ocag 13": PM ae ape ee 
From a tadpole of Bombinator pachypus, infected 70 hours. 
Fig. 178. A copulating pair from a tadpole of Bombinator pachypus infected 
70 hours. Acetic-carmine. X 673 diameters. 
Figs. 179 and 180. Two stages in the attempted copulation of a pair of 
gametes from a tadpole of Bombinator pachypus, infected 70 hours. The micro- 
gamete was unusnally large. Later it separated from the macrogamete and formed 
a pseudocyst. Drawn from life. 
Fig. 181. A copulating pair from a tadpole of Bombinator pachypus, infected 
91 hours. The microgamete is attached by the whole anterior half of its body, 
the tail remaining free. This is the only instance in which such a condition was 
seen. The preparation was inadvertently stained before I learned if the conjugation 
would become complete. From life. > 6735 diameters. 
Fig. 182. A copulating pair from a tadpole of Bombinator pachypus, infected 
7 days. There are four chromosomes in the nucleus of the male and four in one 
end of the dividing nucleus of the female. In the other end of the nucleus of 
the female only two chromosomes were visible. Acetic-carmine, magnification not 
recorded. 
Plate XXIV. 
Opalina intestinalis. 
All figures are reduced one-third to the magnification indicated. 
Figs. 183—185a. Copulating pairs in sections of the rectum of a tadpole 
of Bombinator pachypus, infected 60 hours. Figs. 185 and 185a, are from successive 
sections. The macrogamete shown in Fig. 183 was broken as indicated. Coros. 
subl.-acetie acid, DELAFIELD’s haematoxylin. >< 990 diameters. 
Fig. 186. A copulating pair from a tadpole of Bombinator pachypus, infected 
88 hours. One of the two anterior nuclei may be from the male If so it passed 
by the posterior nucleus to reach its present position. Acetic-carmine. X 673 
diameters. 
Fig. 187. A zygote, with the nuclei still unfused, from a tadpole of Bom- 
binator pachypus, infected 7'/, days. Acetic acid. > 673 diameters. 
Fig. 188. A zygote, with the nuclei ready to fuse, from a tadpole of Bom- 
binator pachypus, infected 7 days. Acetic acid. > 673 diameters. 
Fig. 189. A similar zygote from a tadpole of Bombinator pachypus, infected 
$1 hours. Acetic-carmine. > 9YO diameters. 
Fig. 190. A section of a zygote from a tadpole of Bombinator pachypus 
infected 7 days. The two nuclei are still unfused. Coros. subl.-acetic acid, Dxrna- 
FIELD’s haematoxylin. >< 673 diameters. 
