The mass doubling times of exponential-phase cultures of Streptococcus faecalis were varied from 30 to 110 min by omitting glutamine from a defined growth medium and providing different concentrations of glutamate (ranging from 300 to 14 ,Ig/ml). After Formalin fixation, cells were dried by the critical point method, and carbon-platinum replicas were prepared. The surface area and volume of cell poles seen in these replicas were estimated by a computer-assisted, three-dimensional reconstruction technique. It was found that the amount of surface area and volume of poles seen in these replicas were independent of the growth rate of culture from which the samples were taken. These observations were consistent with the unit cell model hypothesis of Donachie and Begg, in which a small number of surface sites would produce a constant amount of new cell surface regardless of the mass doubling time of the culture. However, measurements of the thickness of the cell wall taken from thin sections of the same cells showed that the cell wall increased in thickness as a function of the increase in cellular peptidoglycan content which occurs when the growth rate of this organism is slowed down by a decrease in glutamate concentration. Thus, it would seem that although the size of polar shells made by S. faecalis is invariant with growth rate, the amount of wall precursors used to construct these shells is not. MATERIALS AND METHODSCell growth. Cells of S. faecalis ATCC 9790 were allowed to go through at least six mass doublings in a chemically defined medium (14) (reaching the equivalent of 100 ,ug of dry mass per ml) before being used for study. Mass doubling times (TD) between 30 and 110 min were obtained by removing glutamine and providing a range of concentrations of glutamate (between 300 and 14 ug) (16). Electron microscopy. Formaldehyde prepared from the hydrolysis of paraformaldehyde was added 499 on August 1, 2020 by guest http://jb.asm.org/ Downloaded from 500 EDELSTEIN ET AL.

In a retrospective study of 1,228 white males with histologically confirmed bronchogenic carcinoma, the proportion of squamous cell carcinoma increased with increasing age at diagnosis. Since the distribution of cell types was much the same in the 73% of cases aged 50-69, the relationship of cancer type to daily cigarette dosage was studied in this group. Squamous cell carcinoma increased from 48% of those men who smoked less than 20 cigarettes per day to 61% of those who smoked 40 or more cigarettes per day. Comparison with other studies showed conflicting results.

Immune function was evaluated in 28 non-Hodgkin's lymphoma patients in an attempt to correlate the occurrence of immunodeficiency with the prognostic clinicopathologic factors, lymph-node histology, and clinical stage of disease. Anergy to a battery of recall antigens occurred infrequently (4/28) and only in patients who had Stage IV disease (4/8) (p = less than .004), but did not correlate with lymph-node histology. In contrast to anergy, cellular immunodeficiencies were often detected by lack of response to keyhole limpet hemocyanin immunization in patients regardless of stage. Reductions in at least two of three Ig fractions were found in a third of the patients, with, again, a significantly greater incidence in Stage IV patients (p = less than .005). No significant correlation with histologic type was possible. The response to phytohemagglutinin in vitro was reduced in the patients, but this was of no correlative value.

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