576 PISCES—FISHES, 
animal may remain dormant for many months, ¢.g, from August to 
December. The air seems to pass directly from the mouth of the 
burrow, through the aperture of the capsule-lid (which is produced 
Fic, 309.—Head region of Protopterus.—From W. N. Parker. 
” sat, Sensory tubes ; Z.2., lateral line ;.¢.d7., external gills ; fc.2., 
pectoral fin ; of., operculum. 
inwards in a short pipe) to the nostrils, and thence to the lungs. 
The nourishment appears to be derived from a store of fat deposited 
in the lymphoid tissue around the reproductive organs and kidneys, 
and among the lateral muscles of the tail (cf. fatty bodies in 
Fic. 310.—Larva of Protopterus.—After Budgett. 
e.g. external gills; Pe., pectoral fin; Pv., pelvic fin. 
caterpillars, amphibians, etc.). Moreover, some of the muscles are 
replaced by fat, and others undergo a pathological granular degenera- 
tion (cf. lamprey). To a certain extent, therefore, the dormant 
animal lives on its own tail. It is probable that leucocytes aid in the 
absorption and transportation of the degenerated muscles (cf. tadpoles): 
