232 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Mycetozoa. 



(By A. Lorrain Smith, F.L.S.) 



North Dakota Slime-moulds.* — F. J. Seaver has made a collection 

 of these in connection with the work of the North Dakota Agricultural 

 College, and publishes a list of the species found in the neighbourhood, 

 with descriptive notes. The species were identified and confirmed by 

 T. H. Macbride, of Iowa. 



Sorosphsera Veronicge.j — This organism causes swellings on the 

 stalks of various species of Veronica, and has been referred to the 

 Ustilagineas and also to the Phytomyxineaj. R. Maire and A. Tison 

 have definitely settled its position in the latter group by the discovery 

 of rnyxamcebge in the cells of the host, which divide by successive 

 mitoses and finally unite to form a multinucleate plasmodium. After a 

 time the plasmodium breaks up into uninucleate naked cells, which 

 divide, and the daughter-cells form the spores ; each cell of the host 

 containing a ball of spores. The authors consider the systematic 

 position of Sorosphsera as very near that of Plasmodiophora Brassicse. 



Jaap, 0. — Myxomycetes exsiccati 2e serie No. 21-26. 



[The Myxomycetes were nearly all found by Jaap in Prignitz, and contain 

 fine examples of these organi&ms.] 



Hamburg, 1908. See also Bot. Centralbl., ex. (1909) p. 98. 



Kusano, S. — Photo-chemotaxis of the swarm-spores of Myxomycetes. 

 [On the chemotactic effect of certain acids.] 



Bot. Mag. Tokyo, xxi. No. 250 (1907) pp. 143-53. 

 See also Bot. Centralbl., cviii. (1908) p. 615. 



Schizophyta. 

 Schizomycetes. 



Rate of Multiplication of Bacillus Coli.J — M. A. Barber has 

 studied the rate of multiplication of Bacillus coli at different tempera- 

 tures — using a strain of the organism obtained from the Pasteur 

 Institute, and employing a specially devised warm stage apparatus by 

 which hanging drops containing single bacilli can be separated and 

 observed. The medium used was beef-peptone broth. 



In estimating the rate of reproduction of bacteria, if the number 

 at the start is a, and the number at the end of the observation is b, 



and the number of generations n, then 2" = -, the validity of which 



assumes that each bacillus divides into two nearly equal parts, and that 

 all the bacteria in a culture reproduce at nearly the same rate. The 

 author starts with a single bacterium, so that a = 1, and the formula is 

 simplified to 2" = b. If g be the time required to complete a full 



generation, and t is the time covered by the experiment, then g = -• 



* Bull. Torrey Bot. Club, xxxv. (1908) pp. 577-80. 



t Comptes Rendus, cxlvii. (1908) pp. 1410-12. 



t Journ. Infectious Diseases, v. (Chicago, 1908) p. 379. 



