1 22 Dr. G. C . Wallich on the Value of 



and these Amoebiform sponge-cells of Mr. Carter being s-^Vs-th 

 of an inch in diameter. 



I may observe that few persons will be found to acquiesce in 

 Mr. Carter's opinion (Annals, July, p. 39) as to there being no 

 " necessity for us to concern ourselves about the appearance of 

 the nucleus in A. princeps before it [the young Amcebd] arrives 

 at the size just mentioned/' namely T-i-o^h of an inch in length ; 

 for it will be admitted that we stand but a sorry chance of being 

 able to trace out the development or reproductive process which 

 results in the viviparous parturition recently described by me as 

 occurring in A. villosa, and which forms a most important link in 

 the chain of its vital phenomena, \inless we do concern ourselves 

 specially to investigate the configuration of the young animal 

 even prior to its extrusion from its parent. The failure to do 

 so will assuredly " preclude all possibility " of ascertaining the 

 correctness or otherwise of those highly complicated reproductive 

 phenomena which Mr. Carter has so zealously endeavoured to 

 elucidate. 



I would here mention having repeatedly observed, during the 

 past month, young Arcellce, varying in number from one to four, 

 within the test of the parent. These young specimens were 

 provided with a distinct test, the diameter of which was already 

 so far in excess of that of the aperture of the parent test as to 

 render their escape improbable otherwise than by its rupture. 

 I have also seen what appeared to be full-grown Arcella, exhi- 

 biting every characteristic of the soft parts, but whose test was 

 still soft and membranous, and surrounded the body somewhat 

 loosely. Its surface, however, already presented traces of reti- 

 culation, but, instead of the usual inverted orifice, the margin 

 of the aperture through which the pseudopodia protruded was 

 corrugated externally, giving the structure the appearance of a 

 medlar. Here, then, it would seem that viviparous parturition 

 must necessarily be associated with the casting of the efiete 

 test of the parent and the development of a new one. In other 

 respects, the occurrence of these young Arcellce fully bears out 

 Mr. Carter's detection of young individuals within the test of 

 the closely allied Euglyphce (Annals^ 1856, ser. 2. vol. xviii.) ; 

 whilst in both cases the phenomena may be regarded as analo- 

 gous in their nature to the viviparous parturition described by 

 me as observable in Amoeba villosa^. 



* Perty records having " once seen two round motionless animals in 

 Arcella vulgaris, each having a greater diameter than the mouth of the 

 shell containing them." And he asks if these young Arcellce are set free 

 by the breaking up of the shell. Schultze also cites a similar example as 

 occurring in Gromia Dujardinii. (See Pritchard's 'Infusoria,' London, 

 1861, p. 215.) 



