39 



XXII. S. M. Nasir. "Some Preliminary Investigations on 



the Relationship of Protozoa to Soil Fertility with 

 Special Reference to Nitrogen Fixation/' Annals 

 of Applied Biology, 1923. Vol. X. pp. 122-133. 



A perusal of the results shows that the presence of protozoa 

 has no depressing- effect on the nitrogen-fixing bacteria, either in 

 the artificial culture media, or in sand cultures. From a total of 

 36 experiments done in duplicates or triplicates, 31 showed a 

 decided gain, while only 5 gave negative results. The average 

 figure for fixation works out to be 8.5%, which is well above the 

 experimental error. 



The highest fixation of 30.04% was recorded in sand cultures 

 in the case of ciliates. All the three types of protozoa gave higher 

 fixation figures. The experiment was repeated six times, and 

 every time concordant results were obtained. 



XXIII. D. W. Cutler and Lettice M. Crump. "The Rate 



of Reproduction in Artificial Culture of Colpidiiim 

 Colpoda/' Biochemical Journal, 1923. Vol. XVII. 

 pp. 174-18(). 



Methods are given by which it has been found possible to 

 obtain comparable results when studying the reproductive rates of 

 certain protozoa in mass cultures. 



It is shown that within a relatively short period after inocula- 

 tion, under certain conditions, a varying proportion of the 

 organisms die ; and that this is correlated with the age of the 

 culture from which the inoculation was made. 



By means of three hourly counts it was found that death occurs 

 even during the period of maximum reproduction. 



Evidence is supplied that in certain strains of Colpidium the 

 rate of reproduction from inoculation to the maximum numbers 

 attained is constant. 



XXIV. Madhi.kink Pekev. "Les Protozoaires du Sol/* 



Ann. Sci. Agron., 1923. Vol. LXIII. pp. 333-352. 



A short review is given of our knowledge of soil protozoa 

 together with an account of the species of protozoa found in 

 certain French soils. 



XXV. H. Sandon. "Some Protozoa from the Soils and 



Mosses of Spitsbergen/' Journ. Linn. Soc, 1923. 



Vol. XXXIV. 

 Samples of soils and mosses brought back from Spitsbergen 

 by the Oxford University expedition of 1921 and 1922 were 

 examined, and an abundant protozoal fauna, practically identical 

 with that found in soils and mosses of temperate lands, was found. 

 Protozoa were found to be considerably more numerous in some 

 of the soil samples than in others, but no close connection could 

 be found between the numbers of species present and the physical 

 or chemical properties of the soils. Descriptions are given of 

 seven previously undescribed flagellates, of which five, however, 

 occur also in Rothamsted soils. 



