ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 309 



formation are summarised : — (1) Differentiation of the nuclei in the 

 Plasmodium into two types, small and large ; (2) formation of proto- ■ 

 plasm around these nuclei into two types of cell, small with small 

 nucleus (microcytes), and large with large nucleus (megalocytes) ; 



(3) union of micro- and megalocyte to form the binucleate sporoblast ; 



(4) union and fusion of two sporoblasts to form the four-nucleate pan- 

 sporoblast ; and (5) division of the two megalocyte nuclei to form twelve 

 nuclei (sixteen in forms with four polar capsules), while the two 

 microcyte nuclei apparently remain as the two pansporoblast nuclei. 



Possibility of Milk being infected with Trypanosomes.* — 

 A. Lanfranchi made experiments on pregnant animals by injecting 

 them with several kinds of trypanosomes. and came to the conclusion 

 that Trypanosoma hrucei, T. vodiense and T. gambiense could pass into 

 the milk, and that in the case of T. hnirei and T. gambiense the 

 infection could pass to the offspring. 



Activity of Soil Protozoa. f — George P. Koch gives the results of 

 experiments on Protozoa which exist in the soil usually as cysts, but 

 become excysted with a certain amount of moisture,' and in their 

 active state are believed to be destructive to bacteria. He has found 

 that the most satisfactory method of determining the presence of motile 

 Protozoa is to place on a clean slide a few drops of sterile tap-water, 

 and stir in it, to form a thin tilm, a small portion of soil, at once 

 examining it under the Microscope, for not more than two minutes, on 

 account of the rapid excystment of the Protozoa. He finds that small 

 ciliates, flagellates and amoebas are active in some greenhouse soils, but 

 only occur in small numbers ; that they are not present in field soils 

 normally moist, though all such soils contain cysts, the organisms of 

 which become active with further moisture, while temperature, organic 

 matter and physical properties of the soil are only secondary factors ; 

 that active Protozoa are always present in water-logged soils and in free 

 standing soil-water ; that after heavy rain some Protozoa excyst and 

 remain active so long as the soil is sufficiently wet ; and that under 

 normal conditions Protozoa cannot excyst in 2 minutes, small ciliates 

 doing so in 1 to 2 hours, flagellates in 6 to 8 hours, and large ciliates 

 in 40 hours, all at a temperature of 22" to 24" C. Excystment 

 probably goes on more rapidly at higher temperatures, and the original 

 moisture-content of the soil may also affect the length of time, while 

 different types of Protozoa may prefer different conditions. Further 

 study on this point will be made. 



Leucocytozoon in Ducks. | — A. B. Wickware describes what seems 

 to be a new disease in ducks (in Ontario). The birds show impaired 

 appetite and stupor. When roused they display great excitement 

 and locomotor disorders. The mortalitv was very his^h. An examina- 



*■■ Afcti E. Accad. Lincei, xxv. (1916) pp. .369-73. 

 t Journ. Agric. Research, v. (1915) pp. 477-88. 

 J Parasitology, viii. (1915) pp. 17-21 (3 pis.). 



