454 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



witli sliylitly crimped or folded niaigins, and are soinewbat sunken in liquefied gelatin. (PI. II, 



fig. '».) Under tbe low po^Yer tliey are dense and opaque, with a greeui.sli shimmer in some place.s. 



At margins they are seen to be made up of a felt-worlc of rather coarse fibrils, some of which 



project from the margin, giving it a "frayed" api)earance, while others maybe seen 



floating in the liquefied gelatin as short fragments. 



Gdutiii stab. — Liquefaction begins in cupsliape and s])reads to the tube wall and 

 also downward. (See fig. IC.) When the liquefaction has extended to the tube wall 

 the flow of the liquefaction has the form of a wide angled funnel. There is a faint 

 growth in stab; the liquetied gelatin is clouded exciqit in upper hvyer, which may be 

 nearly clear, while at the bottom there is an abundant yellowish white flocculent 

 sediment. 



Acid (/rlnfin. — (irowth retarded. 



Affdr shiiit. — Grayish white, frosted looking, rather dense strijie, with wavy, irreg- 

 ular margins: it is yellowish white by transmitted light; the agar requires a smoky 

 greenish color. 



i>o«((7/o)i.— Clouded with whitish flocculi at surface and a whitish sediment. 

 rotnto. — Thick creamy white, viscid, widely spreading layer, becoming soon yellow- 

 ish, and later caseous in appearance. 



Litmus milk. — Decolorized and a smoky bluish cDlored layer of cloudj' serum at 

 surface and bluish ring on wall of tube; the white portion becomes viscid and jelly-like, and is 

 gradually dissolveil, the layer of serum above gradually increasing in depth ; the reaction is neutral, 

 /^uf/ar gelatin in deep »tab. — Some growth and liquefaction; no gas ])ro(biction. 

 Rosolic acid. — Somewhat decolorized; growth is not vigorous. 



Indol production. — Faint or doubtful reaction; the addition of nitrite is necessary. 

 Relation to temperatiire. — Grows well at the temperature of the room and at 35° to 36° C. 



Fill. 16. 



Bacillus lamosus. 

 (Wurtzt-l bai-illus.) 



Isolated from the water of the Schuylkill Itiver. Not uncommon. It has also Iteen observed 

 in the Delaware water. A large nonniofile bacillus, growing into long segmented threads. In 

 stained preparations these segments are separated by a clear interval, and liave s(juare ends. 

 Forms oval spores in the middle of a segment. 



Colonies in gelatin. — After twenty-four hours the colonies appear as hazy, ill-defined sxjots, 

 with small, indistinct, slightly denser centres. On close inspection they are seen to consist of a 

 loose feltwork; the gelatin is liquetied in a short time. Under a low power a loose network is 

 seen, formed of very long, fine, hair-like filaments, which are sometimes straight and sometimes 

 delicately undulating, running in all directions, and crossing one another at all angles. Toward 

 the center of the "spot" the network is somewhat denser, and here a dark, ill-defined "nucleus" 

 may be found. If the colonies are few in number they may very soon attain a diameter of a 

 centimeter or more. 



Gelatin stah. — The gelatin is permeated by very numerous, long, delicate filaments, which 

 grow out at right angles to the line of inoculation, giving the well-known "inverted fir-tree' 

 appearance which has l)een described, while a thick, wrinkled, whitish layer forms on the surface; 

 liquefaction of all the gelatin occurs after a time. 



Acid gelatin. — Grows less vigorously; there is less development of lateral outgrowths from 

 the line of inoculation; an alkaline reaction is produced in the liquefied gelatin. 



Agar .'ilant. — IJather thick, whitish, dense, felt-like layer, widely spreading and somewhat 

 wrinkled; about the margins thread-like processes maybe seen forming more or less of a network; 

 the agar becomes slightly greenish. 



Bouillon. — Veil-like sheets form a thick, wrinkled, more or less complete whitish mycodeini 

 on the surface, while a membranous sediment settles to the bottom; the reaction is alkaline. 



Potato. — Grayish white, dense, rough, widely spreading layer. 



