ZOOLOaY AND BOTANY, MICEOSCOPY3 ETC. 451 



considerably in size, and after rupture of the membrane a rod-like form 

 appears. This happens at 33° C. in l^-l^J hours. The germs grow in a 

 straight or curved direction with terminal increase, but with very variable 

 degrees of rapidity. In no stage of development was there any evidence of 

 motility. White mice injected with or fed on the spores were unaffected. 

 For this Schizomycete the author has proposed the name Bacillus Brassicse. 



Bacterium of Wheat Ensilage.* — In an examination of wheat ensilage, 

 Dr. O. Katz found three kinds of bacterium and two kinds of mould. One 

 peculiar bacterium is described, having the form ot Streptococcus. The 

 bacteria were cultivated on gelatin plates, and this particular form showed 

 itself as yellowish-white colonies amongst the others, the outline being 

 crenate ; and as growth proceeds, they form white patches, the centre of 

 which is depressed. The chains of micrococcus-like forms stain intensely 

 with methylene-blue, &c. Cultivated in test-tubes, liquefaction takes place 

 in a funnel-like manner around the needle path, being especially active on the 

 surface. Ultimately the whole is liquefied. The bacterium readily grows 

 on sterilized potato. The growth of the Streptococcus is accompanied by a 

 sour smell. 



History and Biology of Pear Blight.f — Mr. J. C. Arthur enumerates 

 the various theories and hypotheses that have been put forward as to 

 the nature of pear blight. In 1877 Professor Burrill first observed the 

 bacteria of blight. In 1882 he characterized the organism under the name 

 of Micrococcus amylovorus. The form of this species of bacterium is very 

 constant under all conditions. The single cells are from oval to roundish- 

 ovoid, and only vary by slight changes in the ratio between their length and 

 breadth ; being from 1 to IJ /x, long, by 1/2 to 3/4 ju. broad, and quite colour- 

 less. For the most part they exist as single independent cells, but may often 

 be found in pairs, especially when still multiplying, and in rare instances 

 are united into a series of four or even more, but never extend into chains. 



By far the most characteristic feature of the life-history of M. amylovorus 

 is the formation of zoogloea-colonies. These have never been observed in 

 the tissues of the tree, under any conditions, or in or upon any sort of solid 

 medium, but they occur with much regularity in fluid cultures, when placed 

 under favourable conditions for rapid growth. The range of substances 

 which may serve as culture media is very wide ; that which on the whole has 

 proved most satisfactory in an infusion of potato. This is prepared by 

 digesting a pared potato in three or four times its bulk of water over a 

 water-bath for a couple of hours. If the heat is allowed to rise much 

 above 70° C, the starch is gelatinized, and it is only with difficulty 

 that the solution can be filtered. Another equally good culture fluid is 

 made by treating corn (maize) meal in a similar manner. The solution is 

 colourless, but it is apt to throw down a troublesome sediment. An 

 infusion of hay gave a nearly normal growth of blight bacteria, but the cells 

 were considerably more refractive than usual. 



As to its behaviour towards staining fluids, the most successful results 

 have been obtained with an aqueous solution of Bismarck-brown, especially in 

 cover-glass preparations. What chemical changes are brought about by its 

 activity in the plant cannot be definitely stated, further than to say that a 

 mucilage or gum, which is soluble in water, is produced in abundance, with 

 the disengagement of carbon dioxide. 



Bacteriuin of rotten Grapes, | — Sig. L. Savastano dissents from the view 

 that the disease of the grape which has been so wide-spread during recent 



* Proc. Linn. Soc. N. S. Wales, i. (1886) pp. 925-8 (1 pi.). 



t Proc. Acad. Nat. Sci. Philacl., 1886, pp. 322-41. 



X Malpighia, i. (1886) pp. 175-83. See this Journal, mitc, p. 129, 



