333 Dr. G. C. Wallich on the Distinctive Characters md 



be urged onwards as before. The same explanation will, I think, 

 be found to. hold good even in the attenuated pseudopodia of 

 some families, as, for instance, the Foraminifera. The essential 

 attributes of sarcode (namely, extensibility and contractility), 

 coupled with the polymorphism evident in eveiy example in 

 which definite form is not partially maintained by the pre- 

 sence of a shell or test, necessarily involve the power of retract- 

 ing as well as projecting these processes, whereas the tenacity of 

 the substance is not such that a pseudopodium once projected 

 can be retracted towards the body in the same way that a piece 

 of rope thrown forwards from a given point can be hauled in 

 again inch by inch. In the broad pseudopodium of Amoeba, as 

 also in the attenuated filament of the Foraminifera, or the still 

 more subtle filament of Acanthometra or Euglyjjha, the process 

 is the same, and is brought about by a reciprocal outward and 

 inward flow of the sarcode-substance ; and thus the granular 

 particles are merely the passive exponents of a vital force which 

 exists quite independently of them. Hence, with all deference 

 to so high an authority as Professor Schultze, I would still re- 

 gard the circulation of granules in the Rhizopods as a pseudo- 

 cyclosis, analogous, I grant, in appearance, but not in origin, to 

 the cyclosis observable in certain vegetable cells, as for example 

 Tradescantia. 



Whilst recently endeavouring to establish the relation between 

 the phenomena of the circulation seen in Amoeba and the cell of 

 Vallisneria, the following very singular facts revealed themselves. 

 As is well known, within each cell of Vallisneriais to be found — 

 in addition to the more watery portion (or, as Mr. Carter has ap- 

 propriately termed it, the " axial fluid "), the layer of very finely 

 granular protoplasm which seems to hug and flow round the in- 

 terior of the wall, and the chlorophyll-granules — a single colour- 

 less mass of protoplasm (of considerable size) which, generally 

 speaking, is only partially afi'ected by the cyclosis, but neverthe- 

 less sometimes flows round with the chlorophyll-granules and 

 occasionally adheres to the peripheral protoplasm so as to form 

 a nodule on its internal aspect. This mass of protoplasm, which 

 has been termed the nucleus or cytoblast, presents at its centre 

 a nucleolus which may be rendered very palpable by the ordinary 

 chemical reagents, but especially so by solution of magenta. 

 Occasionally also some of the chlorophyll-granules form an in- 

 vesting layer over the surface of the nucleus, remaining adherent 

 to it in such a manner as to prove that their presence is not acci- 

 dental. This association of chlorophyll-granules and nucleus is 

 very constant in the mature leaf, but, together with the cyclosis 

 and other phenomena now about to be mentioned, is most di- 

 stinctly visible in the perianth. On examining a delicate Ion- 



