THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 295 
PLATE 15. 
Figs. 1-6. Myxobolus? sp. 41 (after Lieberkiihn; except 1). 
1. Two spores inclosed in the pansporoblast membrane (after Biitschli. x $). 
< about 1050. 
2. Cyst from branchiz of Gasterosteus aculeatus (xX 1). 
3. Free spores from cyst of fig. 2. (x 3.) xX 675. 
4. Another cyst in which spore formation has taken place (x1). x 330. 
5. Another cyst (X 1). xX 220. 
6a-c. ‘‘ Different forms [? developmental stages] of spores” of this species (x 3.) 
Fig. 7a-c. Myxobolus sp. 44. 
7a. Transverse view of spore (after Lieberkiihn in Biitschli. x 3). x 1850. 
7b. Spore with valves separating, giving exit to sporoplasm (after Lieberkiihn. 
Sos) oe wooO: 
7c. Sporoplasm undergoing amceboid movements (after Lieberkiihn. x %). 
xX 1350. 
PLATE 16. 
Figs. 1-6. Myxobolus miilleri (after Biitschli. x 1, except fig. 1). 
1. Two branchial lamelle of a cyprinoid, one containing a conspicuous myxo- 
sporidium. c. The cartilaginous rod supporting the lamella (x #). 
2. A portion of the membrane of fig. 4, more strongly magnified, showing ‘‘ nu- 
cler.7 
3a. Transverse view of spore. 
3b. Transverse view of 2 separated valves. 
4, An isolated small myxosporidium with its membrane. 
5. Nuclei of the myxosporidium. 
6. A series showing the developmental stages of the spore. 
6a. Sporoblast which has segmented into the 2 protocysts and the protosporo- 
plasm. 
b-c. The segments have oriented themselves; the protocysts show beginning 
capsule formation. 
d,e. Later stages of capsule formation. In e orientation of the capsules has 
taken place. 
PLATE OLY. 
Figs. 1-7. Myxobolus miillert (after Biitschli. x 1). 
la. Vertical view; showing capsules, sporoplasm, vacuole and pericornual nuclei. 
1b. Vertical view; showing capsules, ‘‘globules,” sporoplasin, and vacuole. 
-le. Vertical view, showing a common focus-appearance (?focus-illusion), the 
pericornual nuclei apparently attached to the posterior extremity of the 
capsules. Biitschli says the sporoplasm is ‘‘ contracted ” and hence the vac- 
uole is invisible. 
2. Transverse view of spore after action of concentrated sulphuric acid; the 
filaments are extruded and the valves are beginning to gape apart. 
3. Vertical view of spore with extruded filaments, sporoplasm, and ‘‘ globules.” 
4a-d. ‘‘Abnormal” tailed spores; c, spore with 3 capsules. 
5. A separated valve, viewed transversely. 
6. Spore with filaments extruded by pressure. 
7a. Capsule not yet completely developed, with the filament extruded. 
7b. A fully-developed capsule with extruded filament. 
PLATE 18. 
Figs. 1, 2. Myrobolus piriformis and M. ellipsoides (after Balbiani.  X 1). 
~ 1. Section of splenic artery of Tinca tinca, showing on the branches Malpighian 
corpuscles, most of them containing Myxosporidia. 
2. The same, more highly magnified, showing well-developed bicapsulate forms 
(M., ellipsoides) and pyriform unicapsulate or noncapsulate and degenerate 
forms (M. piriformis). 
