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Discharges of bulbar respiratory neurons and electrical activity of the diaphragm and intercostal muscles were studied and pO2, pCO2, pH, and the oxygen saturation of the arterial blood were determined in cats anesthetized with pentobarbital and exposed to the combined action of hypoxia and hypercapnia. During inhalation of a hypoxic gas mixture the developing hypocapnia disturbed the firing pattern of the respiratory neurons and respiration of the Cheyne-Stokes type was established. Addition of 2% CO2 to the hypoxic gas mixture restored the arterial blood gas composition to its initial level, prevented the development of hypocapnia, and prevented the disturbance of the rhythmic firing pattern of the respiratory neurons. Addition of 5% CO2 to the hypoxic gas mixture had a negative action: respiratory unit activity was first stimulated, then inhibited, metabolic and respiratory acidosis was induced, and asphyxia developed.

Mathematical expressions of variability or similarity based on data from pyrolysis-gas-liquid chromatograms were calculated for each combination among three strains of each of nine fasciculatePenicillium spp. The mean similarity for eight of these species clustered around 41 but the similarity forP. cyclopium was 58. Within each of the nine species, exceptP. urticae, at least one combination of strains had a similarity of 51 or greater. Similarities were also calculated for 576 possible combinations among 27 strains used in this study. These data indicate that certain strains of these nine penicillia may be more closely related to strains of other fasciculate species than they are to strains within their own species. This agrees with previous observations on variability and intergradation in the subsection Fasciculata.

During training on the bicycle-ergometer a study was made of the electric activity of respiratory muscles and muscles participating in the work while on the bicycle-ergometer (gastrocnemius and femoral). The study was done on healthy individuals. A close two-way connection is established between the electric activity of respiratory muscles and muscles participating in dynamic work. Stabilization of electric activity occurs earlier in the working muscles than in the respiratory muscles. This fact points to the leading role played by afferent impulsation from the muscles participating in the dynamic work for the elaboration of respiration adequate for this work. On the other hand, a drop of the electric activity of working muscles was seen when conditions disturbing the established adequate respiration character were created in the individuals under study.

Culture extracts produced by 107 fungi isolated from corn grains were assayed by thin layer chromatography for aflatoxin. Certain isolates ofAspergillus flavus, A. niger, A. parasiticus, A. ruber, A. wentii, Penicillium citrinum, andP. variabile produced aflatoxin.Penicillium frequentans andP. puberulum elaborated this toxin only in trace amounts. Bioassays of extracts from 4 of these fungi showed that only the extract fromA. parasiticus was highly toxic.

A. flavus Link, A. leporis States & Christensen, A. oryzae (Ahlb.) Cohn, A. parasiticus Speare, and A. tainarii Kita), A. fumigatus Fresenius, and A. ochraceus Wilhelm were fractionated by polyacrylamide gel electrophoresis. Preparations from A. fumigatus exhibited 48 protein fractions, those from A. flavus and A. oryzae each exhibited 47, there were 43 from 4. parasiticus, and A. ochraceus, A. tamarii, and A. leporis showed 32. 31, and 29 fractions, respectively. Comparison of each of these 7 Aspergillus spp. with one another for homologous protein fractions seemed to indicate that more protein components are shared among A. flavus, A. oryzae, and A. parasiticus than between A. flavus and A. fumigatus. However, comparison between A. fumigatus and A. parasiticus revealed the same number of homologous proteins exhibited by A. oryzae and A. parasiticus. Our results did not support the contention that A. flavus and A. parasiticus may be more closely related to each other than to other members of the A. flavus group. It appeared however that A. flavus and A. oryzae may be more closely related. Protein preparations from all 7 taxa contained 2 common protein fractions. Preparations from the 5 species of the A. flavus group had 2 other common protein fractions not found in A. fumigatus or A. ochraceus. The 3 strains of each of the 7 Aspergillus spp. used in this investigation did not contain the same protein complements. These strains differed only in minor morphological characteristics but may have differed significantly in some of their biochemical processes. Raper and Fennell (1965) recognized 132 species of the genus Aspergillus and separated them into 18 groups. This separation was based primarily on conidial color and morphology of the conidial head. Of all these groups, the A. flavus group may be the most important to man. Its members play a very important role in the deterioration of foods, feeds, grains, and seeds and in the production of aflatoxins. Our interest in the A. flavus group centers around its role in seed deterioration. In our laboratory, we often isolate A. flavus from stored

Seeds of Poa pratensis, Festuca rubra, F. arundinacea, and Lolium multiflorum were stored at 10, 20, 30, or 35°C, and at 35, 55, 75, or 95 per cent r.h. for up to 12 months. Samples stored at 30°C and 95 per cent r.h. and 35°C and 75 or 95 per cent r.h. decreased in germinability after 2 months of storage. At 20°C and either 75 or 95 per cent r.h., seeds decreased more slowly in germinative ability than at the higher temperatures but this decrease was appreciable. Seeds stored at 10°C and at 35, 55, 75, or 95 per cent r.h. germinated well after 12 months. Equilibrium moisture content of the seeds after storage at 35 to 75 per cent r.h. for 2, 4, and 8 months varied little among the four species at each relative humidity level and was not affected by temperature in the range of 10–35°C. Fungi of the Aspergillus glaucus group could not always be isolated from large numbers of seeds in lots that had declined in germinability. Seeds of all four grasses apparently carried superficially-borne species of the A. glaucus group (primarily A. amstelodami) in a ‘dormant’ state at harvest. Members of this group were isolated from substantial numbers of seeds that had been stored for 3 months at 30°C and 75 per cent r.h. These fungi were not isolated from seeds stored for the same length of time at 30°C and 35 per cent r.h.; however, field fungi grew from many of these seeds.

Inhalation of a mixture containing 80% helium and 20% oxygen when respiratory resistance was artificially increased caused the following changes: pulmonary ventilation increased, there was a greater arterial blood oxygen saturation, and intrapulmonary pressure was reduced. The respiratory changes were more pronounced during exercise than at rest.

Acute experiments were carried out on cats. Coughing was induced mechanically by the application of a nylon thread to the mucosa of the nasopharynx and the laryngeal area or to the bifurcation of the trachea and bronchi Electrical activity of the inspiratory and expiratory muscles became much more intense during the cough. Inspiratory activity was predominant during a cough induced by mechanical stimulation of the nasopharynx or of the larynx. The reciprocal relationship between inspiration and expiration was disturbed. In this type of cough the electrical activity of the expiratory muscles was increased at a time when the intrapleural pressure failed to indicate active respiration. When the cough was caused by mechanical stimulation of the mucosa at the bifurcation of the bronchi action potentials of large amplitude and high frequency occurred in long groups of discharges, in which expiratory activity prevailed. Under such conditions the normal relationship between inspiration and expiration were maintained.

The electrical activity of human inspiratory and expiratory muscles was studied in hypoxia, hyperoxia, and hypercapnia during added resistance to respiration. The results obtained confirmed that in man the inspiratory and expiratory zones are reciprocally related. This condition was distinctly demonstrated during changes of the arterial blood oxygen and carbon dioxide tensions. In hypoxic hypoxia and hypercapnia electrical activity of the inspiratory muscles was enhanced, and that of the expiratory muscles reduced. The reverse effect was obtained during the inhalation of pure oxygen.

The pnetunogram and lung ventilation figures do not give sufficient information for judging the rela= tionship between inspiratory and expiratory activity of the respiratory center. It is also important to re cord the electrical activity of the inspiratory and expiratory muscles during the action of various factors on the respiratory center. In earl ier studies published by M. E. Marshak and co-workers the nature of ~ e relationships between the electrical activity, of inspiratory and expiratory muscles was investigated and described in man and animals trader conditio:,s of hyperand hypo~da, of hyl>erand hypocapl~a, and in Cue presence of additional resistance to respiration [5-9].

A colorimetric method to delect captan was modified to permit rapid estimation of this fungicide on individual sorghum seeds. The procedure involves extraction of captan with benzene, removal of interfering dyes with Florisil, reaction with a resorcinol solution, and determination of color intensity with a colorimeter. One hundred seeds from each of 11 commercially treated samples were tested. The seeds numbered from 116,000 to 161,000/ lb. The average amount per sample of captan removed from seeds varied from 10.6 to 28.9 μg/seed and from 0.307 to 1.032 μg/mg seed weight. The theoretical amount of captan should have been 0.975 to 1.400 μg/mg seed weight, according to the container labels. The results indicate the need for closer control of seed treatment and for better definition of amounts of treatment required for adequate seed protection. The method presented now makes it feasible for seed testing laboratories to routinely determine amounts of captan on individual seeds. One technician could probably analyze up to 600 seeds daily, using equipment of larger capacity than the prototypes described in this paper.

Four fungi of the Aspergillus flavus group were differentiated to the species level and strain level by pyrolysis-gas-liquid chromotography. Comparisons of pyrochromatograms revealed more similarities than dissimilarities among both species and strains in the pyrolytic elution patterns. Quantitative analysis was made by comparing the number of peaks in which two strains or reference species agreed or disagreed, the degree of superimposability between the pyrolytic elution patterns of strains and reference species, and the presence or absence of peaks for strain pairs within each species. The accuracy and precision of these techniques suggest that pyrolysis-gas-liquid chromatography may have wide application in the detection, enumeration, and identification of fungi by nonmycologically trained personnel.

Principles of numerical analysis were applied to the interpretation of pyrolysis-gas-liquid chromatography (PGLC) data for characterizing species variation among three strains each of four species of theAspergillus glaucus group. Similarity values for the strains were calculated by comparing the number of peaks in which two strains agreed or disagreed. These data indicate that numerical analyses of pyrochromatograms were closely correlated with conventional taxonomic placement of the taxa with the exception of several intergrading or interbridging forms. Thus, a fundamental unity of these strains can be discerned at the chemical level by PGLC analysis. This unity stems from the similar chemical composition of these organisms, and deviation from this basic composition imparts to these strains their uniqueness and thus permits their delineation into distinct entities or “pyrotypes” based on the peak pattern of the pyrochromatograms.