In the production of Mule-ducks, the author have obtained the following resultsin the fertility tests using the undiluted and diluted semen secured from the Muscovy male by means of the side-collection method.
1. Undiluted semen is superior to various diluted semen in absolute and relative fertility.
2. Fertility potential of the undiluted semen is maintained for 8 days in average, i. e., longer than in the case of the variously (from 3 to 10 times) diluted semen.
3. Eight times as much volume of semen is secured from the Muscovy by means of the side-collection method as by the previously reported electro-ejaculation method. The sperm concentration does not differ greatly between the semen obtained bythe two methods.
4. Judging from the sperm concentration, the volume of the undiluted semen which can be secured from one male at one time is sufficient to provide semen for 89 female birds. Therefore, it does not seem that the injection of undiluted semen reduce the meaning of artificial insemination.

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Twelve female albino rats each nursing six youngs were deprived of their young at ten days after parturition. Vaginal cornficasion and ovulation occured at three to five days after weaning.
When suckling stimulus was reintroduced 24 or 48 hours after weaning, the ovulation was inhibited in four out of ten females or two out of nine females respectively. Ovulation was not inhibited in females which had showed proestrous smear by the next day of re-suckling.
It is suggested from these results that suckling stimulus inhibits the early stage of follicular development.

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Carbon dioxide evolution of the rat ova at the early stage of development from one cell to blastocyst was measured with the Cartesian diver method modified by ANFINSEN. Respiratory quotient was calibrated.
The carbonoxide evolution increased gradually during the development and significant change was observed at the blastcyst stage.
When glucose, α-ketoglutarate and glutamate was added as substrates to the incubating medium, carbone dioxide evolution increased up to 3-4 folds.
Respiratory quotient of the rat ova during the cleavage ranged from 0.90 to 1.03. It seemed to, indicate that the rat ova utilized carbohydrates as the energy source for their development.

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[in Japanese]

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It has been recognized by several workers that antihormone against human chorionic gonadotrophin (Anti-HCG) is produced in the serum of the rabbit receiving inactivated HCG. The purpose of this paper is to ascertain whether Anti-HCG is produced against inactivated HCG in cattle.
1) Preparation of the inactivated HCG: Saline solutions of HCG, containing 300 MU per ml., were inactivated by heating at 95°C in a water bath for 3 to 18 hours. The activity of the inactivated HCG was assayed by using immature female mice. The results of the bioassay were shown in Table 1. Positive responses were obtained in the animals injected with the doses equivalent to 133.3 MU of HCG heated 3 to 12 hours. However, responses were completely negative in the animals injected with the doses equivalent to 200 to 800 MU of HCG heated for 18 hours. From these results, the inactivated ECG used in the present study was prepared by heating saline solution of HCG at 95°C for 18 hours or more.
2) Formation of Anti-HCG in cattle following injection with the inactivated HCG: A Female calf (No. 1) and a cow (No. 2) with normal estrous cycle were used in the experiment. These animals were same as described in our earlier reports I and IV. The serum Anti-HCG in these animals had been determined to be positive 3-100 day after injection with active HCG, but it was determined to be negative at the beginning of the present experiment. The experiment was performed twice in both animals with a interval of 230 and 340 days respetively. Doses of the inactivated HCG injected and times of blood colledtionsfrom them are shown in figures presented under Tables 2 and 3. In the first experiment, each of the animals received the inactivated HCG by single intrnvenous injection, dose being equivalent to 2, 500 MU in No. 1 and 5, 000 MU in No. 2 respectively. The determinations of Anti-HCG were positive for their serum samples collected on the 3 rd to 20 th day after the injection. In the second experiment, they received daily injections of the inactivated HCG for 8 days, the dose being equivallent to 2, 500 and 20, 000 MU in total respectively. Their serum Anti-HCG were determined to be positive on the samples collected 5 and 10 days after the last injection, but they became negative on the 20 th day. In both experiments, the HCG inhibitinh titers of their serum samples were about 1. 5-3. 0 MU per ml. at the maximum level. From these results, it was demonstrated that the antihormone might be produced in cattle by injecting the inactivated HCG, but their HCG inhibiting titers were not so high as those in cattle injected with the active HCG.
3) Neutralization of serum Anti-HCG in vitro: An attempt was made to ascertain whether serum Anti-HCG was neutralized by treating the serum with the inactivated HCG in vitro. The method and results were shown in Table 4.
There was no difference bwtween their HCG inhibiting activities whether or not the serum samples were mixed with the inactivated HCG prior to the determination of serum Anti-HCG.

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