108 W. ARCHER. 



markings. In empty tests (much more frequently met with, 

 so far as I can see, than still retaining the sarcode body) 

 this really appears to me all that is left — at least, all that 

 can be seen. But in the living examples, as Hertwig and 

 Lesser were the first to point out, the concave side is closed, 

 all but a median central opening, by a delicate and hyaline 

 continuation of the test completing the external resemblance 

 to an Arcella. Unlike Arcella, however, not only (when the 

 rhizopod is living) this lower part of the test appears 

 capable of undergoing alteration of figure — sometimes drawn 

 in at the middle, sometimes prominent (like, as say Hertwig 

 and Lesser, " the stomach of a Medusa"), but also the whole 

 test can assume various, by no means inconsiderable, altera- 

 tions of figure, even so much that the two opposite parts of 

 the periphery of the disc of the test may become bent down- 

 wards or doubled towards each other so as almost to touch. 

 When in this temporary position such an example would 

 very much resemble Greeff's figure of the supposed form of 

 " Amphizonella " which he called " A. flava.^' It almost 

 seems as if the stolon-like sarcode processes passing from 

 the body-mass, and inwardly attached to the angle of the 

 test, acted as " muscles " in causing its contraction, and 

 that on the withdrawal of the force it recovers its normal 

 form by virtue of its own elasticity. 



The body-mass does not fill the test, but sends off several 

 of those " stolon-like " sarcode processes to the (inner side, 

 of course, of the) periphery of the test, similar to Arcella 

 and Difflugia. The protoplasm is minutely graniilar, and 

 (near the margin) usually show several contractile vacuoles 

 and a median nucleus. Hertwig and Lesser record that 

 between the test and the body-mass occur some coarsely 

 granular pigment of the colour of " diatomin.'^ Without 

 venturing to contradict so accurate observers, I would myself 

 merely suggest that this colour seems to reside wholly in the 

 test ; it is quite as deep, and even brighter in empty tests, as 

 when the organism is living, 



I have several times watched a living example with the 

 hope of seeing the projection of the finger-like pseudopodia 

 described by Hertwig and Lesser, but have never seen this, 

 possibly due to their being very short, that is, not extending 

 beyond the periphery of the shell, as, indeed, those authors 

 describe. 



The only mode of reproduction observed by Hertwig and 

 Lesser is by encysting, the body-mass becoming balled to- 

 gether into a spherical figure, the result of Avhich they 

 could not follow out. I have also noticed an encysted state. 



