The effect of age on body energy content of the annual cyprinodont fish, Nothobranchius guentheri.

Bomb calorimetry measurements were made on dried whole body samples of N. guentheri in an attempt to detect the effect of age induced protein crosslinking. The results show a clear decrease in body energy with increasing age. However, this decrease was larger than expected and was probably due to a slight decrease in body fat component with increasing age rather than crosslinking alone.

Critical size of newborn homeotherms.

It is shown that for cylindrical and spherical bodies there is a critical radius below which the addition of any form of insulation to the body will increase rather than decrease the cooling of the body. It is proposed, therefore, that it would be thermally detrimental to newborn homeotherms to be born with a protective covering (fur or down) if their body size were less than this critical size, and consequently that the degree of natal covering is not necessarily related to the overall development of the species when the birth size is less than this critical size. A critical weight is derived from the critical radius for basically spherical animals which compares favorably with typical birth weights of various altricial homeotherms. The effect of the overall conductive-convective heat transfer caused by a basically cylindrical animal rolling up into a ball is also discussed.

Contractile Characteristics of Mimosa pudica L.

The force-velocity characteristics of the primary pulvinus of Mimosa pudica have been determined using a new polytonic measurement technique. The contractile characteristics were determined from a modified form of Hill's equation (Hill, A. V. 1938. Proc. Roy. Soc. London B126: 136-195) describing the physiological contractile behavior of animal muscle. The values of the resulting Hill's constants were found to be remarkably similar to those of intact animal muscle and reconstituted contractile collagen.