FINE STRUCTURES OF THE CARBON MONOXIDE SECRETING TISSUE IN THE FLOAT OF PORTUGUESE MAN-OF-WAR PHYSALIA PHYSALIS L.)

¹ Biology Department, Tulane University, New Orleans, La. 70118, and the Marine Biological Laboratory, Woods Hole, Mass. 02543.

1. The carbon monoxide gas-secreting tissue (pneumadena) of Physalia is a single layer of ectodermal cells that are cuboidal to columnar in morphology. There is only one specific type cell and it is characterized by having the distal part, adjacent to the gas-interface surface, packed with large mitochondria. The mitochondria are unique in having few and small cristae. Most of the internum of the mitochondrion is occupied by a granular matrix. Compared with other secreting cells, there is very little smooth endoplasmic reticulum and less rough endoplasmic reticulum. There are numerous Golgi complexes and complex multivesiculate bodies. The nucleus is often enveloped by a cisternal space.

2. The secretory epithelium is sensitive to adverse factors such as lowered temperature and presents changes that, though degenerate in appearance, may still have some functional ability to produce carbon monoxide. There is no evidence to indicate conclusively that gas is secreted by formation of vesicles in the cytoplasm. Therefore, it is assumed that carbon monoxide is secreted by diffusion from the cell surface which is frequently thrown into finger-like projections.