Experiments were carried out to confirm whether the gpc strain might be useful in the assay of tetanus toxoids of various types. It was shown in this experiment that the doses-response lines of various toxoids including the international standard tetanus toxoid were proved parallel and the reproducibility of the assay was very high. These results as well as those reported before suggested that gpc strain was most suitable mice for tetanus toxoid assay available in Japan. However, significant discrepancy was often observed in the relative potency between mouse method and guinea pig method and the reason of this phenomenon was discussed, and it was suggested that the final solution of such problem should be carried out by the clinical trials in the future.
We have proved on the corelation between proportional weights of hormonal organs and the ages of rats (Wistar-King A and Wistar strain) . Results are stated in the following: a negative corelative coefficient is shown by proportional weights of the hormonal organs of the upper part of the neck, a positive corelative coefficient is shown by the organs of abdominal part and no corelation of the thymus is recognized. It seems that these corelative coefficients are different by the locations of organs in the body.