1872.] 



Modes of Origin of Infusoria fyc. 



245 



flagellum, and its subsequent movements, were impaired by the glare of 

 artificial light to which the organism was subjected, cannot be said. 

 Certainly, however, the flagellum seems to be thrown out much more 

 rapidly in other cases. Speaking of simple organisms of this kind, Dr. T. 

 R. Lewis says*: — " Frequently a succession of pseudopodia are seen pro- 

 jected in a wave-like manner, as if lashing the fluid." And, again, of other 

 similarly active animalcules he says : — " Sometimes one flagellum is seen, 

 a posterior one, at others an anterior one also, both being retractile at 

 will ; and another may be darted forth out of any portion of its body." 

 Again, where tailed "zoospores" are produced from Algee or from such 

 Fungi as Achlya and Oystopus, they are also evolved most rapidly — 

 two hours often sufficing for the entire production of a brood of such 

 flagellated Monads from the segmentation of a mass of formless pro- 

 toplasm. 



Monads, indeed, are frequently produced from the "pellicle" in pre- 

 cisely the same manner as that by which they arise within the terminal 

 chambers of certain Algae or Fungi — that is to say, they result from the 

 segmentation of a mass of homogeneous protoplasm f. The steps of this 

 process I will now describe. 



An infusion of hay was made with water at a temperature of about 120° 

 F., and maintained at this heat for three hours. After filtration, four or 

 five ounces of the fluid were poured into a wide-mouthed bottle, and 

 placed under a small bell-jar. When the infusion was examined at the ex- 

 piration of three days, it was found to be quite turbid, and covered a mo- 

 derately thick pellicle. On removing portions of this and submit^ £ it to 

 microscopical examination, the fluid around was found to contain multitudes 

 of very active specimens of Monas lens, having an average length of 3-3V0 '• 

 The pellicle itself was mostly composed of medium-sized Bacteria, though 

 here and there were areas, of different dimensions, in which the units had 

 more the appearance of embryo TorulcB. But, contrasting with the very 

 pale fawn-colour of the evenly granular pellicle, there were numerous areas 

 of a whitish colour, refractive, and more or less homogeneous. These areas 

 differed very much in shape and size; some were not more than y^Vo"» 

 whilst others were as much as T -JV in diameter. Their shape was wholly 

 irregular. Careful examination with a T V and a -Jt" immersion-objective 

 made it easy to recognize such transitions as are depicted in fig. 2. As in 

 the instances previously recorded, the first appreciable stage in the forma- 

 tion of an embryonal area in the pellicle was a local increase in the amount 

 of gelatinous material between the units of this portion of the pellicle, so 

 that they became more distinctly separated from one another than in adja- 



* Report on the Microscopic Objects found in Cholera Evacuations &c. (Calcutta, 

 1870), pp. 26 & 33. 



f In both cases, also, it happens that the products of segmentation are sometimes 

 motionless and sometimes active units. 



VOL. XX. T 



