LIFE-HISTORY OF BUCEPHALUS HAIMEANUS. 687 
PLATE 39. 
Fic. 1.—Bucephalus haimeanus viewed from the dorsal surface as a 
transparent object. Body slightly compressed by a cover slip. (Zeiss 4 D.) 
m. Mouth. 
Fic. 2—Young sporocyst from gonad of oyster. (Zeiss 4 D.) 
Fic. 3.—Slightly older sporocyst, through the transparent walls of which 
cercaria in various stages of development may be seen. 
Fic. 4.—Germ tubes (branches of sporocyst) from an oyster in an advanced 
stage of infection. 
Fic. 5.—Branching end of a germ tube. 
Fic. 6.—Section of infected oyster tissue passing transversely through a 
germ tube. (Only a sector of the tube is shown.) 
Fic. 7.—Longitudinal section of the growing end of a germ tube. Cells 
in this portion of the tube are undifferentiated. 
Fic. 8.—Longitudinal section of old germ tube. (Ouly one side of tube is 
shown.) 
Fic. 9.—Longitudinal section of developing cercaria (from lumen of germ 
tube) in which the tail rudiments have made their appearance. Structure of 
parenchyma nuclei is not represented. 
Fie. 10.—Transverse section of the body wall of a mature cercaria. 
Fic. 11.—Longitudinal section of the body wall of a mature cercaria. 
Fic. 12.—Longitudinal section of an encysted form found in the gills and 
beneath the body-epithelium of the oyster. 
Fic. 18.—Horizontal longitudinal section of a developing cercaria. (Older 
than that shown in Fig. 9.) 
Vic. 14.—Section of infected oyster tissue. (Zeiss 4 A.) 
Fie. 15.—a. Section of germ tube with germ cell protruding into lumen of 
tube. 
a’, Germ celi with first polar body. 
6. Germ ceil with first polar body dividing. 
ce. Germ ceil, first uivision. ‘Three polar bodies may be seen on the 
Surlace. 
d, Germ cell, second division (3-cell stage.) 
e. Germ cell (4-cell stage). 
jf. Germ cell (5-cell stage). 
g- Germ ball enclosed by a membrane which is formed by the union of two 
flattened cells. 
Fie. 16.—Longitudinal section of germ tube, showing a germ cell giving 
off a polar body within the wall. The polar body has divided. 
