16 
advancing mass shews a deep border of clear unwriukled yielding sarcode, 
whilst the portion of ectosarc at the opposite side of the body is contracted 
into firm folds ; the endosarc takes at first no active part in contraction, but 
is impelled forwards as the advancing front yields and spreads out. The 
ectosarc alone performs the functions of muscle envelope, such as is seen in 
mollusca. In comparison, therefore, with the sarcode of the water Amoebse, 
this ectosarc shows an advance in special function approaching that of 
muscle. 
Is this enveloping ectosarc invested with membrane ? Greef maintains 
that it is not, and further that its inner surface or border is not sharply 
defined, or separated from the inner sarcode. The lines and folds seen on 
the exterior are occasioned by the compression resulting from the construc- 
tion of the ectosarc, which Greef conceives to have acquired a muscular 
character, though nob strictly possessing the appearance of a muscle 
substance. The reactions of acids, alkalies, iodine, &c, do not indicate the 
existence of any membrane. The inner mass is a granular soft protoplasm, 
not contractile. In it are seen transparent vacuoles, either in bubbles or 
cavities, filled with fluid. These are of various size, and change place quickly 
under pressure of contractile action. They sometimes run together, forming 
a large bubble, at other times break up into a number of smaller ones. When 
the creature is motionless, a large bubble will slowly work its way to the 
periphery, then break into a group of smaller vesicles w hich gradually unite 
again into a bubble of the original size. They can, therefore, have do mem- 
branous wall, and are not contractile. 
In the endosarc are found other contents — diatoms and algas, taken in as 
food. Besides these there are seen highly-colored yellow or brown particles 
which have often a distinct form, and contain a distinct nucleus. Sometimes 
these particles are agglomerated together, and the whole group is surrounded 
by a clear space. Sometimes a diatom or alga is included. Greef thinks 
these colored particles subservient to digestion of food, and compares them 
with the yellow cell-like bodies of many lower animals (so called liver cells) 
— in any case they are not a portion of the reproductive system. 
Other crystalline particles are also seen, which Greef considers to be 
excretion. Auerbach, Wallich, Carter, and others, have seen the same kind 
of particles in all Amoebse and certain Ehizopods. 
Every Amoeba has a nucleus, and generally but one. This has no regular 
position, is soft, and is of an oval shape. It is composed of — 1st, a capsule 
or transparent membrauous envelope ; 2nd, a tough and thick second coat, 
apparently supplied with pores (that is to say, the substance is broken at 
ntervals by radial lines) ; 3rd, an internal plasm, structureless and homo- 
