238 SUMMABY OF CUEBENT EESEABCHES BELATING TO 



The Eotatoria are divided (1) into those in which the female 

 always has, and those in which it has not an anal orifice to the 

 intestine ; (2) the former into (a) those that are permanently fixed, 

 and (/3) those that are free-living; (3) the former of these into 

 (i.) separate, (ii.) colonial forms ; the latter into those in which (i.) the 

 body is rounded and apparently unsegmented, and (ii.) the body is 

 saccular or flattened with apparent segments. Into the further details 

 of this somewhat artificial classification we have not the space to follow 

 the author. 



After reviewing the opinions of previous writers as to the systematic 

 position of the Eotatoria, Eckstein points out that their direct 

 alliance with the Annelida is opposed by the early appearance of 

 segmentation in those forms ; the view of Korschelt and Metschni- 

 koff that the Eotatoria are allied to the Turbellaria by Dinophilus is 

 affected by Graff's belief that that genus is a true Eotifer. The 

 author would associate with the Eotifera the Gastrotricha, but, in 

 truth, their systematic place is even more indefinite than that of the 

 Eotifera themselves. 



Rotifer within an Acanthocystis.* — Dr. A. C. Stokes' account of 

 an observation of a rotifer living within the rhizopod Acanthocystis 

 chcetophora is not perhaps written with any severity of scientific style, 

 but it is evident that any abstract we could give of it would fail to con- 

 vey a correct idea of the original. It is also the first instance of which 

 we are aware, of astronomical time being applied to microscopical 

 observations. 



" Eecently one of these spinous creatures \_Acanihocystis] appeared 

 under my Microscope. It seemed to be alive and well, but within it 

 near the armoured surface, was a semi-transparent moving something 

 that was too active to have a right there. As the motions of this 

 foreign body became more impulsive, it turned completely over and 

 showed itself to be one of the rotifers. In size it equalled not more 

 than one-third the Acanthocystis^ diameter, but dwarfish stature was 

 amply compensated by nimbleness. 



With a leap, prodigious for so small a creature, the rotifer dashed 

 against the wall and hurled the rhizopod down the field, while the 

 silicious spines snapped and flew. If the scene was exciting to the 

 spectator, what must it have been to the Acanthocystis, with that 

 jumping Jonah leaping among its vitals ? It was no joke to either 

 party. A struggle for life was going on under my very eyes. The 

 rhizopod, with every particle of its jelly-mass surrounding the rotifer 

 possessing digestive power, seemed calm, perhaps with the calmness of 

 despair, but the rotifer — oh how she plunged ! Not a moment did 

 she rest, not a muscle did she leave unused, not a manoeuvre untried. 

 The situation appeared a bad one for that rotifer, since she bade fair 

 to be digested. She stretched herself and forced out the spinous 

 armour until it seemed on the point of rupture ; the Acanthocystis simply 

 flattened the opposite side and waited, digesting. The rotifer leaped, 

 she turned, she pushed with her two sharp toes against the wall ; the 



* The Microscope, iv. (1884) pp. 33-5. 



