MYXOBACTERIA 71 



Most of the specimens described are from America ; one species 

 is recorded from Liberia, in Africa ; and Zukal has recently found 

 in Vienna four species of Clionihuiniicea identical with tliose dis- 

 covered by Tliaxter; he has also described one new species — 

 MyxococcKs mucrosporun. 



The specimen I have had under observation ^^rew on some 

 pellets of rabbit-dung on which I was watching froui day to day 

 the development of Dicti/osUdiuin, one of the near allies of the 

 Mt/j:ohacteria. The pellets were gathered, on account of their 

 very mouldy appearance, at Llanwymawddwy, in Merioneth.shire, 

 towards the end of the long dry season of 1899. They were put 

 away in a dry place for several weeks, then moistened and kept in 

 a damp atmosphere. Numerous fnngi soon made their appearance, 

 and in due course the cysts of what I now know were Myxobacteria. 

 They looked exactly like the minute perithecia of some species of 

 Nectria ; they were of a bright pinkish-orange colour, and grew in 

 large numbers over the pellets. They were easily distinguishable 

 with a small-power field-glass. A closer microscopic examination 

 showed that the perithecia-like bodies were formed entirely of 

 micrococci that were colourless when dispersed; there was no 

 trace of fungal hyphse, and they could only be bacteria. I tried to 

 cultivate the cocci in a hanging drop of sterilized decoction of the 

 pellets, without success. Tube-cultures were also tried with a 

 mixture of the decoction and gelatine, and these resulted in small 

 spherical colourless colonies distributed in the gelatine after a few 

 days, On examination these were seen to be formed of actively 

 motile rods. An attempt was made to cultivate some of the bacteria 

 from the colonies on carefully sterilized pellets, and so establish a 

 relation between the different forms ; but this was, for unknown 

 reasons, also unsuccessful. The coloured cysts first observed had 

 disappeared meanwhile, and the whole matter was laid aside. 



In the Xatura/ist for November, 1900, I observed a reference by 

 Mr. Massee to Prof. Thaxter's work on Mi/xohacteria, and recognized 

 the nature of the cocci. I have no longer any doubt that the motile 

 rods in the culture-tubes were a stage of the encysted cocci. Tne 

 species differs in form and colour from the members of the genus 

 already described, and is therefore an addition to the growing 

 numbers of Myxohacteria, 



L ^ 



oooo n^ 

 o ^ u^ 



B 



Myxococcus pyriformis. — A. Cysts magnified about 50 diameters. B. Cocci 

 from the cysts. C. Rods from tlie colonies in the culture-tubes, both magnified 

 2400 diameters. 



Myxococcus pyriformis, sp. n. Cysts scattered, pear-shaped, 

 minute, varying in size, about ^ mm. in height, bright pinkish- 

 orange-coloured, on a short transparent gelatinous stalk composed 



