NOVEMBEE 18, 1898.] 



SCIENCE. 



693 



oval, rod-like bacillus, 0.6 to 0.8 by 1 to 6 /-i, 

 •constant in diameter, but varying greatly 

 in length. Occurs singly, or in young cul- 

 jtures in pairs, chains or masses. Stains 

 readily with the ordinary aniline dj'es, 

 either in water or alcoholic solution. Has 

 no capsule, but is supplied with several 

 iflagella scattered over the surface and is 

 actively motile. Does not produce spores. 

 On nutrient beef and potato broth produces 

 first a strong turbidity and a slight granular 

 pellicle, which breaks up and settles to the 

 bottom. The color of the mass is milky 

 •white on all solid media. On agar plates 

 the surface colonies at ordinary tempera- 

 tures (18° to 20° C.) reach a diameter 

 ■of about 1 mm. in 48 hours and at the end 

 ■of a week become 5 to 6 mm. across. A 

 temperature of 36° to 37° C. starts the 

 growth more promptly, but results in a 

 fetbler ultimate development. The addi- 

 tion of malic or citric acid in small amounts 

 so as to feebly acidify the agar increases the 

 vigor of growth, while an excess of alkali 

 •diminishes it. On gelatine made from the 

 common brands the opposite effect is pro- 

 duced. Gelatine should be neutral to phe- 

 nol phthalein to insure vigorous develop- 

 ment. There is a moderate liquefaction in 

 :good gelatine cultures. A moderate growth 

 is made on sterile cooked potato cylinders. 

 In the fermentation tube it decomposes 

 ■sugar without the formation of gas. It is 

 most vigorous with maltose, the cultures 

 becoming strongly acid, and is slightly less 

 «o with cane sugar, dextrose and laevulose. 

 It is aerobic and facultative anaerobic. It 

 produces no pigment or coloring matter of 

 any sort, and no odor. It does not decom- 

 pose starch. Its principal food consists of 

 nitrogenous matter, sugars and probably to 

 some extent certain organic acids — to wit, 

 the substances found in young growing 

 tissues of its host. Certain statements 

 formerly made are known to be erroneous. 

 The germ mass was said to be yellowish- 



white on potato. This could only come 

 from an impure culture, as the true pear- 

 blight germ is always white. Gas, or in 

 some places carbon dioxide gas, is said to 

 be formed. This never occurs. Butyric 

 acid is said to be one of the products of its 

 decomposition. The germ produces acids, 

 but never butyric. Starch is said to be de- 

 composed and used as food, but, so far, the 

 author has not been able to demonstrate 

 this. The germ is said to live over winter 

 in the soil. The author has failed to find it 

 in the earth, and its life cycle is complete 

 without such hypothesis. 



On the Occurrence of a Yeast Form in the Life 

 Cycle of SphcBropsis malorum. Peofessor 

 Wm. B. Alwood. 



Paper records the discovery of a yeast 

 form in laboratory cultures of this fungus. 

 On isolation and inoculation on the fruit of 

 the apple the common fruit bodies character- 

 istic of *S^. malorum made their appearance. 



Some Steps in the Life History of Asters. Pro- 

 fessor Edward S. Burgess. 



This paper presents results of field- 

 studies of Aster variations made during the 

 last twelve years. Its purpose is to review 

 certain known terms in the ontogenj' of 

 Asters which are liable to misinterpreta- 

 tion. These sources of confusion are of 

 three classes, the first of which is the num- 

 ber of leaf-forms normally developed at 

 once upon a single stem. There are eight 

 principal forms : 



a. Primordial leaf, usually roundish and 

 transient. 



b. Radical leaves, two or three or more, 

 often progressively different. 



c. Lower cauline leaves, usually the most 

 characteristic. 



d. Middle cauline leaves, usually transi- 

 tional in shape. 



e. Upper cauline leaves, usually much 

 smaller. 



