Hearts from eight adult dogs were perfused through both coronary arteries with methylmethacrylate. Small specimens cut out from the left ventricular wall were eroded in 50% HCL for 5-7 days. The replicas were studied under the SEM (S-450). The main results were outlined as follows: The subendocardial capillary plexus composed of varied shapes and orientation of meshes was present. The capillary network of the myocardial layers was consisted of many parallel capillaries and between them a variety of models of anastomoses, such as "H" "K" and "8" modes etc, were observed. In our findings, it was demonstrated that the arteriole and venule were distributed between the myocardial bundles and their direction was often perpendicular to the myocardial bundles. The postcapillary venules were poured into venule by the "ginger or turnip root" arrangement. The replicas of the Thebesian veins were proved in our specimens. The A-V shunting was not observed.

Three fresh kidneys removed from three adult bodies were perfused through the renal artery with 5％ and 10％ ABS (a copolymer of allylcyanide, butadiene and styrolene). Small specimens removed from the kidney were digested in 50％ HCI. Cast replicas of renal arteries and their branches were taken and examined with SEM (S-450 or S-520). The results were as follows.The capillary network of the area of the polar cushion cell were observed at the hilum of glomerulus in our casts. Their appearances are triangular, tetragonal or comma-like. In general, the shape of the meshes of the capillary network was round, oval, triangular or tetragonal. The diameters of the meshes were smaller than that of the vessels themselves. The microvessels of the area of the polar cushion cell, which mainly originated from the afferent arteriole, were continuous with the capillary of the glomerulus. The afferent arteriole was often traveled in the central part of the area of the polar cushion cell. The function of the microvessels of the area of the polar cushion cell was discussed in this article.

Two fresh kidneys removed from two male adult bodies, about 48 hrs. after death, were injected through the renal artery with ABS (a copolymer of allyl cyanide, butadiene and styrolene) at a constant pressure between 250-280 mmHg. Corrosion casts were prepared for the study of glomerular vasculature. Small specimens were cut out from the kidney were digested in 20% HCl and 10% peptic solution. Cast replicas of renal arteries and their branches were removed and examined with the SEM (Hitachi H-500 with Scanning accessories HSE_2). The chief results of observation were as follows: The corrosion-cast models of adults' glomerular vessels observed under the SEM consisted of two kinds: the spherical glomerulus and the chrythsanthemum-like glomerulus. The system of capillary loops of the spherical glomerulus was interconnected by anastomosed vessels. The lobular patterns of the glomerular capillary loops as described in the mouse kidney by Hall were not observed. The chrythsanthemum-like glomerulus consisted of many branches of capillaries, either longer or shorter, and most ended blindly. No more than one efferent or afferent vessel have been observed in our corrosioncast specimen of the adults' glomerular vessels. In general, the afferent and efferent arteriole enters or exits at the hilum of glomerulus. Rarely, the efferent vessel left the glomerulus at the oppositeside of the hilum. By-pass tract between the afferent and efferent vessels was not found in our casts. Constrictions of the afferent arterioles such as those shown in rats by Shonyo and Mann ('44) were not demonstrated in the adults' kidneys. Sometimes, there is a constriction near the point of origin of the afferent arteriole.

Three fresh lungs removed from three male adult dogs were injected with ABS. This material was injected into each lobe of the lung through the pulmonary artery and bronchus simultaneously. The pressure was maintained between 200～280 mmHg. The injected specimens were digested in 20～50％ HCl and peptic solutions for 7～10 days. A part of the cast replicas of the lungs was taken off and gilded with EIKO IB-3. Under SEM (HITACHIS～450) the specimens thus prepared were observed. The chief findings were as follows:Scanning electron micrographs of the injected vascular system presented a clear, three-dimensional picture of extensive capillary networks around the individual alveoli. In the septa between alveoli the capillary networks appeared to be a single layer. These networks looked like pentagonal or hexagonal rings; the meshes in between them were smaller than the vessels themselves.The capillaries observed here in the scanning stereopicture belonged to the category of the alvioli cappilary of the subpleura; the meshes of which were larger than those of other parts.Because the numerous alveoli and capillary networks surrounding the alveoli were filled with the ABS, the position and the shape of the capillary networks can be seen very clearly.The lumen of the alveoli were polyhedron in shape, various in sizes and smooth in contour. Many imprints of the alveolar type Ⅱ cell nuclei existed on the surface. The bridge formation between alveoli were really interalveolar pores; their number and diameter varied. The function of the interalveolar pores was briefly considered in this paper.