Carrageenans in the cell walls of Chondrus crispus Stack. (Rhodophyceae, Gigartinales) II. Birefringence

Positive values of intrinsic birefringence were obtained with respect to circumferential directions in the cell walls of fixed but unstained sections of Chondrus crispus. With respect to the same directions, negative values of birefringence were obtained in sections stained with toluidine blue (the ‘topooptical reaction’). These results suggest that the carrageenan occurring in the walls contributes to their intrinsic birefringence, and that the orientation of the carrageenan molecules in the cell walls is similar to that of the microfibrilsseen by electron microscopy, i.e. parallel to the surface of the wall, but random in face view.The intrinsic birefringence of the cortical and subcortical intercellular matrix was positive, and the topooptical reaction negative, with respect to the direction of the cell rows. Cortical and subcortical birefringence in the tetrasporophyte is more extensive than that in the female gametophyte. This difference may be used to differentiate the nuclear phase of non-reproductive plants.