474 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Schizophyceee. His observations were chiefly made on living material 

 stained with very dilute methylen-blue. A large number of different forms 

 were investigated, with the conclusion that there are present a number 

 of stainable granules in many Bacteria and in Schizophycese a peripheral 

 pigmented layer and a colourless central body. The author believes, 

 however, that, contrary to the opinion of Biitschli, there is not the least 

 evidence that the granules of bacteria have any connection with a 

 nucleus ; they are of varying number, can be seen to arise in the proto- 

 plasm, and never divide. The pigmented layer, he concludes, cannot be 

 considered as a true plastid on account of its indefinite limits towards 

 the inside, and the fact that it may contain both gas and liquid vacuoles ; 

 there is no doubt, however, that it functions as a plastid. Massart 

 further considers that there is no reason to consider the central body, 

 in which he has never seen any trace of karyokineses, as of nuclear 

 nature. The fact that it has no definite outline, is sometimes vacuo- 

 lated, and that it becomes greatly increased in size when the cell becomes 

 a spore, all militate against the view that it is a nucleus. The author 

 believes that there are two types of cells, those with cytoplasm and a 

 nucleus, and simple cells such as are found in the Schizophyta. The 

 paper concludes with a discussion of the relation of the various groups 

 of the Schizophycero and the relation of the Schizophyta to other low 

 forms of life. The conclusion is reached that the latter forms must be 

 considered as an isolated group of doubtful origin and with no known 

 affinities. 



Schizomycetes. 



Experimental Production of Parasitic Races of Bacteria. * — 

 Lepontre attempted to show that the micro-organisms responsible for 

 bacterial diseases in plants need not necessarily be " specific," but that 

 ordinary saprophytic bacteria might acquire parasitic properties. In 

 the course of this work he endeavoured to so modify the B. fluoresceins 

 liquefaciens, B. mycoides, and B. mesentericus vulgatus, as to enable ttiem 

 to lead a parasitic existence in various vegetable tissues. An experi- 

 mental field, (the same one Laurent employed in 1898 when working at 

 the same subject) used for growing carrots, potatoes, turnips, &c., was 

 divided into five plots numbered 1. to V., and each year plot I. was 

 treated with an excessive dose of nitrogenised manure ; plot II. with 

 potash manure; plot III. with superphosphates; plot IV. with lime; 

 and plot V. with chloride of sodium. 



Discs from carrots grown in each of these five plots were inoculated 

 with pure cultures of each of the bacilli and incubated at 30° C. Those 

 obtained from plots I. and IV. gave the most luxuriant growth, those 

 from III. the most scanty. Successive passages of the bacilli, from 

 carrot to carrot, resulted in increased ease and luxuriance of growth, 

 and finally the carrots from plot III. were attacked as readily as those 

 from the other plots ; the growth of the B. fluorescens in about 24 

 hours converting the vegetable tissue to the depth of 5 mm. into a 

 brownish alkaline fluid. The organisms were now transferred from 

 carrots to turnips with analogous results. Of artichokes inoculated 



* Coniptes Kendus, exxxiv. (1902) pp. 927-9. See also Ann. lust. Pasteur, xvi. 

 (1902) pp. 301-12. 



