Using data from a blank experiment with wheat it was found that the regression of the logarithms of the variances for plots of different areas on the logarithms of their areas was approximately linear. A graphical review of variances, etc., reported in the literature for thirty-nine other blank experiments indicates that the results of most such experiments conform to the same law.

It is shown that the above law can be generalized (so as to be applicable to any size of field) by applying a certain adjustment to the regression coefficient b', so as to give a modified coefficient b applicable to an “infinite” field.

From this generalized relationship there has been deduced an expression ((4), p. 16) to indicate average relative efficiencies to be expected for randomized block experiments with varying numbers of plots per block in a field for which the coefficient b is known.

A formulae (5), which may be used to estimate the most efficient size of plot for any given experiment, has also been deduced. The cost of using plots of other than the most efficient size is indicated graphically in Fig. 7.

1. The porosity of egg is measured by the usual practice of estimating the weight loss under standard conditions. The porosity coefficient is expressed as the loss in weight in mg. per sq. cm. of egg surface per 24 hr. at 37°C.

P coeff.=mg. cm.2 24 hr. 37°.

2. It is shown that eggs of even curvature approximate closely to the ideal mathematical form of two hemi-prolate spheroids, differing in their eccentricities and meeting in the plane of their common minor axes. On this assumption the divergence between the observed and calculated long perimeter is only +0·618 per cent (five eggs) and between the observed and calculated volumes+3·78 per cent (seventy eggs).

3. It is explained how, by taking the specific gravity of the egg to correct for departures from the theoretical form, it is possible to calculate the surface area with an error not exceeding 1 per cent.

Further studies of the behaviour of cellulose-splitting bacteria in artificial media have been made in an attempt to account for the manner in which cellulose is utilized for fat production in the ruminant. The behaviour of thermophilic bacteria, with an optimum temperature of fermentation in the neighbourhood of 65°C, has been compared with that of the micro-organisms capable of fermenting at 37°C. In both cases the cultures were obtained from the rumen contents of sheep.

By the addition of toluene at the “head” stage of fermentation, it was possible to demonstrate, both at 37 and 65°C., the production of small amounts of glucose during subsequent incubation. Glucose is clearly a primary breakdown product in the bacterial fermentation of cellulose.

An investigation has been made of the nature of the volatile fatty acids produced by bacterial decomposition of shredded filter paper. No consistent differences from this standpoint were noted between the reactions as carried out at 37 and 65°C., but the nature and proportions of the acids varied considerably from culture to culture. In some cases acetic acid was produced almost exclusively, whilst in others the fatty acids consisted of butyric and formic acids, with but traces of acetic acid. The findings in this regard apparently afford no clue to the manner in which cellulose is used for fat production, since propionic acid, the only recognized fat-former among the lower normal fatty acids, was not detected.

Thirty-one laporotomies, in addition to a number of confirmatory operations, were performed to determine the time of ovulation in the ewe. It was found that (1) ovulation did not occur during oestrus, (2) in ewes with oestrous periods lasting 30 hr. or more ovulation occurred a short time after the end of oestrus and that the time of its occurrence is related to the end and not to the beginning of oestrus, and (3) there is a minimum period of approximately 23–25 hr. before which ovulation does not occur, irrespective of the duration of oestrus.

1. In an examination of Park Grass soils extending over 3 years, and in shorter studies of other grassland soils, the fresh soil always contained more ammonia than nitrate nitrogen. The levels of both were low, and in spite of minor fluctuations were sufficiently constant to suggest the existence of equilibrium conditions in the nitrogen cycle. Climatic factors had no appreciable influence except on one very acid plot; here frost or drought, severe enough to kill the herbage, allowed ammonia to accumulate. Otherwise, treatment had little effect, but liming tended to give higher ammonia and lower nitrate levels. The equilibrium levels of both ammonia and nitrate were higher in old grassland soils than in land newly put down to grass.

2. “Mineralizable” nitrogen, produced by incubating the fresh soils under standard conditions, showed a seasonal rhythm the opposite of the annual temperature rhythm, tending to a maximum in winter and early spring and a minimum in summer and early autumn. This was related to the addition and decay of organic residues in the soil. An abnormally dry summer caused a temporary rise, especially on the more acid plots. An extremely acid plot, on which a mat accumulated in the field, produced as much mineralizable nitrogen on incubation as more normal soils.

3. Ammonia and nitrate production on incubation differed greatly with different treatments, apparently as a result of the influence of treatment on soil reaction. The more acid soils, with pH less than 6.0, produced chiefly ammonia, while the less acid soils produced chiefly nitrate. There was a significant correlation between reaction and percentage nitrification.

A method of obtaining samples of semen from rabbit males by means of a dummy and artificial vagina is described. The volume of the semen, and the number of spermatozoa per cm. (density) and the total number of spermatozoa in the sample have been measured. The data obtained from these measurements have been analysed under the following headings:

1. Relation between total volume and total number of spermatozoa. With an increase in the total volume of the ejaculate there is an increase in the total number of spermatozoa, but the relationship is not linear. The density of spermatozoa varies considerably.

2. Seasonal variation. Seasonal variation in sperm production is not marked in these data. There is slight tendency for the numbers to be highest in the early part of the year and lowest in August and September when the animal is moulting.

3. Individual variation. In each individual, variation is considerable. Differences between individuals are not marked, but as most of the animals were of low average fertility, it is probable that this result is not typical of male rabbits in general.

4. Effect of successive matings with in a short period. In successive matings the number of spermatozoa diminishes rapidly. As the density is not much affected, the diminution is due to reduction in the volume of the ejaculate.

5. Relation between the number of spermatozoa in the ejaculate and the number in the various sections of the spermatic tract. After a series of samples had been obtained, some males were killed and an estimate made of the number of spermatozoa present in various parts of the tract. From the results it is concluded that on ejaculation the vas deferens is practically emptied and that some sperm in the ejaculate come from the cauda epididymis.

6. Observations on sexual behaviour. The sexual pattern of the male rabbit is described and the relation between sexual stimulation and sex drive is discussed.

1. Studies lead to the conclusion that Chibnall-preparations of pasturage proteins, in spite of their small amounts of carbohydrate impurity, may yet yield, on hydrolysis by mineral acids, practically the right amounts even of most of those amino-acids which are adversely affected by carbohydrates to some extent when tested singly under the conditions.

2. Preparations made in another way after treating the pasturage with ether as in the original Chibnall-method showed features of interest in the problem of attaining very pure proteins now much needed for purposes of comparison.

3. A new method is introduced by which it is possible to compare what may be extracted from the protoplasm of fresh unpulverized pasturages with the composition of the natural saps on a unit weight basis.

4. Production and breakdown of protoplasmic protein in perennial rye-grass during growth consistently appeared related to variations in the content of “nitrogen” and phosphates in the saps and the supplies of “nitrogen” and phosphates from the soil.