Many modifications of the agar diffusion technique for the analysis of serum protein components have been developed since the original techniques were described by Oudin (1948) and Ouchterlony (1948) . Grabar and Williams (1955) developed a method combining electrophoresis and diffusion of serum proteins in agar and produced precipitin lines using appropriate anti-sera. Various investigators have developed two-dimensional electrophoresis of serum proteins using both paper and starch-gel techniques (Durrhum, 1951; Kunkel and Tiselias, 1951; Poalik and Smithies, 1958) .
The following report is a description of our method of applying two-dimensional electrophoresis to immunoelectrophoresis in agar and results culimating from this method. Two new techniques designed to aid in the identification of the various serum proteins detected by immunoelectrophoresis are also described.

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In the previous papers, it was shown that the ability of diphtheria bacilli to develop infection at the mucous membrane varied greatly depending on the strain used and this characteristic was independent not only of thein vitro toxigenicity but also of the in vivo toxigenicity (Murata et al., 1959; Akama et al., 1961) . Then arose the question of whether the antitoxic immunity alone would be enough to protect the individuals from the infection due to virulent diphtheria bacilli or some other factors would be necessary for complete protection. In connection with this problem, O'Meara (1940) stated that antitoxin containing antibody to B substance produced by gravis strains was more effective for the protection of diphtheria. The report of Ipsen (1946) showed that individuals who showed fairly high antitoxin titers in their sera were also affected by the disease. In regard to the active immunization, Frobisher and his colleagues (1943, 1947) reported that rabbits immunized with living nontoxigenic diphtheria bacilli developed significant resistance to the subsequent challenge of the toxigenic strain. However, they did not measure the antitoxin titer less than 0.01 unit per cc, whereas such a low level of antitoxin as 0.003 unit per cc might influence the resistance of the immunized animal. Nor did they refer to the latent state of antitoxic immunity which seems very important in the discussion of infection. Since then many other investigators (Scheibel, 1950; Bowen et al., 1954; Lautrop, 1955) reported on the role of antibacterial immunity in experimental diphtheria. In these cases as well as in the experiments by Frobisher et at., however, the challenge was carried out by the cutaneous infection by the living bacilli which seemed, to the present authors, to be greatly different from the infection via the mucous membrane. The authors have tried to analyse the mechanisms of the immunity in diphtheria by the challenge method simulating to the natural infection where the conjunctiva was used as the site of infection. Evidences were obtained that both the antitoxic (passive and active) and antibacterial (active) immunity were effective in the prevention of the infection by diphtheria bacilli at the conjunctiva of guinea pigs.

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In the previous paper (Takano et al., 1961), the fundamental behavior of several human cell lines to ⁶⁰Co γ-irradiation was described on the basis of dose-response curve estimated by the cell population 7 days after irradiation. The human uterus cancer HeLa strain was subjected to irradiation with a dose of 2000r, and surviving cells were grown to form colonies. As the result, a cell group developed with a little increased tendency in radioresistance.
In the present study, the irradiation and cultivation were repeated up to 5 times or 10, 000r in the accumulated dose, and some stable changes in radioresistance and other biological characters of the HeLa cells were revealed to have occurred.

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Development of insecticide-resistance among Japanese mosquitoes was first reported by Suzuki et al. (1958, 1959) in regard to the adults of Culex pipiens porllens against chlorinated hydrocarbons.
Subsequently, during a period from 1959 to 1960, samples of mosquitoes were collected from various sources in Tokyo area by the present author, and their resistance level to insecticides was investigated.
The present paper deals with the results of the laboratory work carried out with the larvae and adults of several populations of Culex pipiens and with the larvae of certain populations Culex tritaeniorhynchus, Aedes albopictus and Armigeres subalbatus.

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The author (1959) found that when the cysticercoids of Raillietina kashiwarensis entered the digestive tract of the chicken, the digestive enzyme, especially trypsin, played an important role in causing the excystment of the cysticercoids. But on the other hand, it is necessary to examine what effect is exerted by the osmotic pressure in the alimentary tract of the chicken upon the excystment.
Up to the present time, as to the excystment of the tapeworm bladderworm, only the effect of the digestive juice has been examined but no study on the effect of the osmotic pressure upon the excystment has practically been made except the author (1958) who made it clear that the osmotic pressure does not give any important influence in causing the excystment of Raillietina echinobothrida cysticercoids.
So, the author examined in vitro what role the osmotic pressure in the alimentary tract of the chicken plays in causing the excystment of the cysticercoids of Raillietina kashiwarensis.

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As the technic for testing the susceptibility of Oncomelania snails to molluscicides two different methods are available; one is the plate method devised by McMullen (1949) and the other routine immersion one. The former was particulary devised for the screening purpose of molluscicides but is now utilized for the quantitative test of the susceptibility of snails. Considering theoretically, however, the latter would be better for the purpose, because the former, though simple in the procedure, implicates some shortness, which lies in the fact that here the snails get contact with chemicals only with a part of her body, that some snails move off the moist filter paper and that at times some of them ingest a considerable amount of filter paper. All such appear to interfere with the reproducibility of the effects. From such a viewpoint as mentioned above, a comparative examination on both methods was carried out.
For the establishment of the standardized technic, moreover, experimental study should be conducted to standardize the following subjects: a) the suitable length of time during which snails are in contact with chemicals, b) the suitable temperature at which snails are in the solution, c) the amount of the solution per snail during the test, d) the time of examining snails for their death. And finally the reproducibility of the standardized technic should be examined.

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Among the dog parasite, there are several common species to human parasites, such as gnathostome, trematodes, some cestodes, etc.. The prevalence of such dog parasites has the important meanings for the incidence of human parasites too. Some larval forms of dog parasites, such as dog ascaris or dog hook worm, according to Beaver (1956) et al., enter man, causing some serious diseases of larval migrans. So the epidemiologic survey of dog parasites is very useful for the establishment of eradica-tional schedule on such human parasites.
At the time of experimental work on hook worm, whipworm, or many other parasites, the collection of living materials from the dog is much easier than that from man, even though there are slight differences between dog parasites and human parasites. So the faunistic knowledge of dog parasites in some area is of benefit to carry out such experiments. Moreover it is possible to get some analogy between the dog and man concerning the parasitic phenomena of each parasite.
From the viewpoint of veterinary, there are several serious diseases caused by dog helminths, such as hook worm, filaria, gnathostoma, spirocerca, or another trematodes and cestodes. So it is important to examine the incidence of such dog parasites for the control of dog diseases.
Up to the present time, no data have been reported on the dog parasite in Bangkok, though there are many stray dogs in the city. For the above mentioned reasons and also by the academic interest, one hundred stray dogs in Bangkok were autopsied to examine their parasitic helminths in 1960 and 1961. The obtained data were compared and discussed with that reported by Ito et al. (1958) in Japan.

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Tetrachlorethylene has been used with success for a long time in the treatment of hook-worm infection. In 1958 Goodwin et al. made clinical trials with bephenium hydroxynaphthoate on a group of patients in Ceylon and claimed that it was better than tetrachlorethylene by higher in efficacy and less in toxicity. Since then there were many reports mentioning the satisfactory results of bephenium (Nazaly et al., 1959; Ahmid et al., 1957; Hahn et al., 1960; Hsieh et al., 1960; Jung et al., 1960; Young et al., 1960) . Recently in Japan a new drug known as bromo-naphthol† was reported to be a superior grade anthelminthic (Yoshida et al., 1961, personal communication) . The authors were very much interested in these drugs especially in the last one, and had an opportunity to try them on the labourers and their families of Na-Bon Rubber Plantation in Nakorn-Sritharmaraj Province, South Thailand. This report revealed the successful results.

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