EXTRACrS AND ABSTRACTS. 375 



coloured forms as well as various colourless ones are developed. A. 

 common species is — 



Monas Okenii, of which the Danish examples are not so deeply 

 coloured as are those figured by Cohn ; marine specimens are oval or 

 cylindric and straight, fresh -water ones somewhat spiral in form ; 

 smaller individuals have a single posterior cilium, the larger one at 

 each end. As to division, Prof. Warming believes that only the small 

 ones exhibit it ; occasionally very long cells were found, but they 

 were not constricted in the middle, and showed no sign of division. 

 This does not appear to exhibit a " zooglea" state. 



Spirillum violaceum, Warm. — Found in brackish water, is 

 very near Monas Okenii, but the spiral is more pronounced, the 

 endochrome is of a dull violet colour, the granules are finer than those 

 of M. Ohenii, and but few sulphur-grains are present ; the extremities 

 bear a cilium, and the movements are more vivacious than those of 

 M. Okenii. 



Forms referred to Ophidomonas sanguinea show scarcely more than 

 three spiral turns ; sometimes only one cilium is seen, in other cases 

 there is a cilium at each end, and occasionally two or three cilia, not 

 always occupying a median position, are found at one of the ex- 

 tremities. 



Under the name Bacterium sulfuratum are united a number of 

 forms, which together make up the chief part of the red colouration. 

 The states in which this appear are : — 1. As s'gh.eres {Monas vinosa, 

 Ehrbg.). 2. As roundish bodies, usually with a constriction and with 

 granules grouped at the ends (Monas Warmingii, Cohn). 3. Like 

 Monas vinosa, but crowded with sulphur-grains {Monas erubescens, 

 Ehrbg.). 4. Long, narrow, cylindrical, and filled with sulphur- grains 

 {Rhahdomonas rosea, Cohn). Finally, the series is brought to a close 

 by a spiral form, the amount of torsion varying from scarcely anything 

 to more than one complete turn. Prof. Warming is at a loss to know 

 what becomes of the large forms ; he thinks it possible that they form 

 a sort of spore like Aseococcus, or become still more enlarged, cast off 

 their cilia, form transverse partitions, and become Beggiatoa. 



Monas gracilis, Warm., grows only in fresh water ; it is straight 

 and rounded at the ends, and its plasma is a little paler than that of 

 M. Okenii. 



Spirillum Rosenhergii, Warm. — This is a very quick-moving 

 species, of a dull colour, and with a sharply-pronounced spire ; it is 

 almost always filled with sulphur- grains which are devoid of the red- 

 dish colour found in its allies ; also no cilium was observed on it. 



All along the Danish coast-line grows Merismopedia liUoralis, of 

 which families were found consisting of from one to sixty-four tetrads 

 of cells. 



Several species of Beggiatoa are found in immense quantity on 

 quite flat shores and in the canals of Copenhagen. To a new form is 

 given the name B. minima ; it is very small, agile, and flexible, with 

 fine articulations, grayish in colour, without sulphur-grains, and with 

 vermiform movements. Associated with B. miralilis, Cohn, was a 

 smaller eciliate condition, without septa, and with great capacity for 

 division ; this is looked upon as being the young state of B. mirabilis, 

 and the term " germs of Beggiatoa " is applied to simple spherical 



