Summary A series of experiments was performed in an attempt to establish the anatomical localization of the effects upon uterine movements and ovulation due to the stimulation of the amygdaloid complex. A remarkable change in the uterine movements was recognized through electrical or chemical stimulation of delimitd parts of the amygdaloid nuclei in dogs, cats and rabbits. In pxtpartum and in non‐pregnant matured animals, as well as in the latter half of pregnancy, an increase of tonus in uterine musculature and auginentation in frequency and amplitude of uterine motility can be evoked through unilateral stimulation of the medial principal amygdaloid nucleus (T of Völsch). These effects vary more or less according to the animal species and rather greatly by the stadium of sexual cycle at the time of experimentation. Stimulation of the lateral principal nucleus (M of VöZsch), the intermediate principal nucleus (T' of Vösch), the so‐called cortical amygdaloid nucleus (B of Vösch), the medial amygdaloid nucleus (D of Vösch) and the central amygdaloid nucleus (E of Vösch) seems to be altogether ineffective. Stimulation of the periamygdaloid cortex gives an equally hardly effect upon the uterine motility. The impulse from the amygdala passes very likely through fibers corresponding to MV or MD fiber described by Fukuchi in Ungulata or through so‐called medial forebrain bundle and is led to the viscero effective centre of the hypothalamus. The electrical stimulation of nuclei T and T' of the amygdala is capable of producing ovulation or hemorrhagic follicle in the ovary of the matured estrous rabbit. The impulse seems to go from the amygdala directly to the ventro medial nucleus of the hypothalamus leading further to the anterior pituitary lobe. The further effect to the ovary may be governed by the gonado tropic hormone released from the anterior pituitary lobe. In this latter case the estrous phase of the animals may also play an important rôle. (This work was aided in part by a grant from the Science Research Foundation of the Educational Department.

Summary Through bilateral destruction of the amygdaloid nuclear complex in infant and adult animals and through subsequent observations under careful feeding in sxne period of time, following results were obtained:  By bilateral amygdalectomy in infant animals, inhibition in the growth was induced in most cases.  Histological observations on the brain lesions of these cases reveal that the inhibitory effect upon the growth may be initiated seemingly by destruction of the medial amygdaloid complex such as nuclei B, D or T, or periamygdaloid cortex such as Pam2 and Pam3, or the anterior amygdaloid region, especially at the level of the nucleus of the lateral olfactory trac:.  The inhibitory effect upon the growth was exceedingly obvious in those cases, in which the amygdaloid regions or surrounding structures of these most effective parts of the amygdala were extensively damaged on both sides.  Somewhat accelerating effect upon the growth was found in some cases, however, no positive evidence could be gained by any means in this series of observation.  Unilateral arnygdalar or hypothalamic destruction cannot result in retardation of the growth, even in those highly convincing cases with tissie deterioration in the vicinity of the amygdala.  An example of remarkable obesity was found in an adult cat following bilateral destruction of the medial parts of the amygdala and a part of the entorhinal area. Histological alterations of the internal organs of this case were described and a functional relationship of the so‐called feeding centre in the hypothalamus was discussed.

We intended to destruct bilaterally the hippocampal regions or amygdala in infant and adult animals to get some effective disturbances in growth, food intake, behavior, sexual cycle and other conditions in the autonomic nervous system. This report is only a preliminary one, because the investigations are now in progress in our laboratory. We had already made some experiments upon amygdala and reported on the inhibitory effect upon the growth of infant animals or on the obesity in adult cat induced by bilateral destruction of the amygdaloid nuclear region.z,3) The inhibitory effect upon the growth was exceedingly obvious in those cases, in which the medial amygdaloid complex such as the cortical, the medical or the basomedial group or surrounding structures of these most effective parts of the amygdala upon the sympathetic nervous system were extensively damaged on both sides. We noticed, however, in some cases somewhat accelerating effect upon the growth with no reasonable evidence and also found no sign of retardation of the growth in those examples of unilateral amygdalar or hypothalamic destruction. Further we had an example of remarkable obesity in an adult cat following bilateral destruction of the medial parts of the amygdala and a part of the entorhinal area3). It must be noticed that the destruction in the medial or anterior part of amygdala results in growth inhibition in infant animals and in obesity in adult ones. The effect of destruction of amygdala seems to be influencing hypothalamic equilibrium of autonomous functions in such a way that disturbance of the latter leads to malgrowth in infants and to obesity in adults in definite cases.

Summary The results of comparative‐anatomical and experimental studies on amygdala disclosed the following facts: 1) The division of amygdaloid niiclei into two groups, basolateral and corticomedial seems to be not fully adequate in regard to the functional differences, because results of the stimulation experiments in our laboratory indicate for certain coincidence of effectiveness with autonomous function. From the view angle of fiber connection, this way of division ought also not to be highly evaluated. 2) The intermediate principal nucleus (nucleus T of Völsch large‐celled lateral part of the basal nucleus of American authors) is generally divided into two parts, namely, dorsal and ventral portions. The ventral portion of that of the bat is particularly large and together with the large lateral principal nucleus nucleus M of Völsch, lateral nucleus of American authors) constitutes a characteristic of bat amygdala. The reason for its largeness was found, by means of destruction experiment of the amygdaln, in a close connection with the flight activity. Presumably intermediate prinripal nucleus participates in the extrapyramidal motor function; the lateral principal nucleus is generally large in most animals and functionally seems to inhibit motor activity. 3) The medial principal nucleus (nucleus T of Völsch, small‐celled medial part of the basal nucleus of American authors) remains maldeveloped in some lower animals. In general, it grows distinctly larger in the caudal level. According to the result of the investigations undertaken in our laboratory, the said nucleus is chiefly related to autonomic nervous system. The above mentioned lateral and intermediate principal nuclei (T and T) also seem to have some relation, partially at least with autonomic nervous system. 4) The so‐called medial nucleus in higher animals (D of Völsch) is generally maldeveloped. This nucleus, together with cortical nucleus (B of Völsch), participates partially also in autonomic nerve function. The central nuclei of higher animals (E and E of Völsch) are also underdeveloped 5) The periamygdaloid cortex (Pam1, Pam2 and Pam3 of Rose) receives the fibers from the lateral olfactory tract and evidently participates in olfactory function, but it also causes both extrapyramidal and autonomic reflexes probably by way of the amygdalar connection. Of the said cortical portions what are particularly closely related with amygdala are the portions Pam2 and Pam3. However, the portion Pam3 has not been differentiated yet in the lower animals. 6) When the bilateral amygdala of a young animal is destroyed early in life, growth gets markedly inhibited. In such an animal. atrophy of the parotid gland, thyroid gland, hypophysis, adrenal gland and pancreatic gland was observed. As the cause of this developmental disturbance there are two nervous routes assumable, namely, the route through amygdala → hypothalamus → anterior lobe of hypophysis → general inner secretory glands and the route through amygdala → salivary glands → inner secretory disturbance o...

Phylogenetically, the so-called cerebral olfactory system in the wider sense seems to have morz to do with the vegetative function than as a system for somatic sensation. Concerning amygdala, Herrick assumed from his study on Amphibia that.