Biochemical studies on Aerobacter cloacae have been carried out by many workers. Recently, according to the advanced opinion and definite judgment of Edwards, A. aerogenes was classified into the Klebsiella group (Kauffmann, 1951) and A. cloacae into the Cloaca group of Castellani and Charmers (Kauffmann, 1954) . On the other hand, Edwards and Fife (1955) proposed to name the group “Aerobacter ”, since the name Aerobacter has been more commonly used than the name Cloaca and Aerobacter could not be clearly separated from Klebsiella. The present authors (1957) reported that typical Cloaca cultures in amino-acid decarboxylation tests were differentiable from Klebsiella and other similar cultures by means of biochemical tests.
In spite of its distinct biochemical properties, serological studies so far performed on. this group gave only unsatisfactory results. Edwards and Fife (1955) described that, among A. cloacae cultures studied, a half of them were encapsulated, 30% of the latter being typable with Klebsiella capsular sera. The authors (1957) concluded, however, that the organisms of the Cloaca group were generally acapsulated and definitely differed from. encapsulated motile Klebsiella-like organisms in amino-acid decarboxylation and sugar fermentation tests. Stuart, Wheeler, Rustigian and Zimmermann (1943) studied the former organisms biochemically and serologically by the name of paracolon Aerobactern without any account for O and H antigens of the organisms. Deacon (1952) found 12 O and 6 H antigens in the cultures of biotype 32011, which had been described by Stuart and his co-workers, and other related cultures of slowly lactose-fermenting A. cloacae by antigen analysis. Eveland and Faber (1953) also studied biotype 32011 serologically and established 21 O and 22 H antigen groups. However, it was assumed by Edwards and Ewing (1955) and confirmed by the authors (1957) that biotype 32011 belonged to the Hafnia group but not to the Cloaca group. Therefore, any of the serological studies made in the past can not afford information for establishment of the systematic serology of the Cloaca group,
The present studies were carried out to obtain sufficient information on the serological characteristics of the Cloaca organisms.

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The antibacterial action of chlortetracycline against vegetative cells and spores of Cl. botulinum type E in minced fish flesh was investigated by Boyd et al. (1956) . Control of type E, fish-borne botulism by treating fish with chlortetracycline-ice has been proposed by Dolman (1957) .
In Japan, almost all of the outbreaks of human botulism have resulted from consumption of “izushi”, which is a preserved foodstuff consisting of raw fish, vegetables, and cooked rice. Investigation for prolonging storage life of fish with antibiotics has been carried out and practical application of chlortetracycline has been approved in some countries including Japan. The purpose of the present study is to investigate the possibility of preventing the “izushi”-borne, type E botulism by treating fish with antibiotics.
This paper deals with some experiments with oxytetracycline in culture media and also in fish with spores of a strain of Cl. botulinum type E.

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In experiments of Pneumococcus transformation, several media have been devised in an attempt to improve the reproducibility of results ever since the in vitro reaction was first carried out by Dawson (1931) . It has been recognized that the occurrence of the in vitro reaction requires some environmental factors, in addition to the nutrients necessary for the initiation and maintenance of cell growth (McCarty et al., 1946) . Rabbit serum or human serous fluids provided such factors in many cases (E-Taylor, 1949; Austrian, 1952) . Hotchkiss and E-Taylor (1951) pointed out that bovine albumin could substitute the factors. However even in the presence of these factors, a reproducible and stable result was not necessarily secured in the Pneumococcus transformation. In order to obtain a constant and regular result in this reaction, it will be necessary to supply a better qualified medium and appropriate factor (s) . At the same time, elucidation of the nature of such factor (s), if any, will be significant to an understanding of the mechanism of the transformation reaction.
During the course of experiments performed in our laboratory on Pneumococcus transformation from SM sensitive to resistant cells, using heart infusion Neopepton broth as a basic medium, it was found that an addition of albumin and of horse blood hemolysate gave good results, while irregular results were obtained with the addition of albumin only. The experiments performed to ascertain the nature of the substance (s) in the hemolysate will be presented below.

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It is generally recognized that most of snake venoms manifest proteolytic activity (Zeller, 1951) . Several reports have recently been accumulated (Deutsch et al., 1955; Rao et al., 1956; Hadidian, 1956; Henriques et al., 1958; Maeno et al., 1958) to suggest the presence of more than one proteolytic enzymes in certain snake venoms.
Up to date, comparatively numerous informations have been available on the pharmacological function of the potent proteolytic enzymes of the Crotalidae venoms. Hemorrhage and necrosis are claimed to be attributable, at least in part, to the action of proteolytic enzymes (Houssay, 1930; Kellaway, 1939; Zeller, 1948; Porges, 1953; van Heyningen, 1954; Slotta, 1955; Kaiser et al., 1958; Maeno et al., 1958) . In our recent studies (Ohsaka et al., 1960, 1961) it was reported that zone electrophoretical fractionation, coupled by a new quantitative method for estimating hemorrhagic activity (Kondo et at., 1960), of Habu venom revealed the presence of at least two hemorrhagic principles, both of which were associated with proteolytic activity on casein. Eagle (1937) and Jánszky (1950) demonstrated a parallelism between the proteolytic activity of venoms and their blood coagulating activity. The proteolytic enzymes may also contribute to the hypotensive action of snake venom, resulting in shock, through damage given to vascular endothelium with consequent escape of blood from circulation (Kellaway, 1939; Porges, 1953) or through the liberation of bradykinin from serum globulin (Rocha e Silva et al., 1949; Prado et at., 1950) .
In view of the pharmacological function of proteolytic enzymes of Crotalidae venoms above-cited, and of the fact that such venoms also manifest lethal toxicity, it becomes of obvious interest and significance to know whether or not proteolytic activity in Habu snake venom can contribute to its lethal toxicity.
The experiments here reported indicate that at least the main part of lethal toxicity and of proteolytic activity on casein were independent of each other. Evidences suggesting the presence of several proteolytic enzymes in this venom will also be presented.

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Hemorrhage is one of the most prominent manifestations produced by the parenteral administration of various snake venoms especially of Habu (Mitsuhashi et al., 1959; Ohsaka et al., 1961) and other species of Crotalidae (Fidler et al., 1940; Taube et al., 1937) . In order to study the principle (s) responsible for hemorrhage caused by snake venom, a quantitative method for the determination of hemorrhagic activity is required. Up to date, however, few attempts have been made to establish the quantitative estimation of hemorrhagic activity of snake venom. Minton (1956) and Mitsuhashi et al. (1959) tried to estimate the hemorrhagic activity but the results they obtained were not reproducible in our hands.
The present authors proposed a new method, which consists of the following procedures; (1) intracutaneous injection of venom into the depilated back skin of rabbits; (2) accurate measurement of the size of hemorrhagic spot carried out from the inside of the removed skin; (3) application of the parallel line assay method for the estimation.
By this method it was possible to study the relationships of hemorrhagic activity to proteolytic and other pathological activities of Habu venom (Ohsaka et al., 1960, 1961) . In this paper, details of the new method will be presented.

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One species of Apharyngeal Brevifurcate Distome Cercariae was obtained by the author from fresh water snails, Semisulcospira libertina (could) in Shizuoka Prefecture. This. furcocercous cercaria was identifiable with that reported by Yoshida (1917) who obtained it from the same species of snail in Tokushima Prefecture. A tentative name “Cercaria G” had been given for this cercaria by Yoshida, and then it renamed as Cercaria scripta by Faust (1924) .
According to my present experiment this cercaria proved to be infective for the chicken of Gallus gallus domesticus by the injection method, and a number of worms were discovered from their mesenteric vessels. The worms apparently belonged to the genus. Pseudobilharziella Ejsmont, 1929, and were identifiable with P. corvi Yamaguti, 1941. The detailed morphology and life cycle of this species are presented in the present paper.

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Fresh water snails, Semisulcospira libertina, including S. reiniana and S. japonica, are known as the first intermediate hosts of pathogenic trematodes, e. g. Paragonimus, Metagonimus, etc. These snails are also infected with many other non-pathogenic cercariae, the majority of which have been described up to now incompletely. Therefore, in the case of epidemiological studies, research workers used to be confused on the differentiation of cercariae.
In order to correct such meagre descriptions, the author have already carried out many investigations regarding the morphology of carcariae. More than 18 species of cercariae were detected from Semisulcospira libertina by the author in the past ten years, 1949 to 1959. Ten species of them were already described in details (Ito, 1950, 1952 a, 1952 b, 1953 a, 1953b, 1956, 1958, 1959, 1960) .
In this paper, another seven species of cercariae are presented and described on their morphological differences; i. e, two furcocercous-, one echinostome-, one xiphidio-, two tailless-, and one cysticercous-cercaria. Among them, four are the redescriptions, while the other three are given a new name respectively.

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In the separate paper (Ohsaka et al., 1961) it was reported that zone electrophoresis provided evidence for the presence in Habu venom of at least two hemorrhagic principles, designated as HR1 and HR2, both of which were associated with proteolytic activity on casein. The present experiment is directed to confirm the difference between HR1 and HR2 in the zone electrophoretical mobility and to examine further the possible correlation between hemorrhagic and proteolytic activities by repeat electrophoresis.

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