SCIENTIFIC SUMMARY. 
327 
placed in a higher stage in the great division of the Rhizopoda. From 
facts such as these F. E. Schulze conceives he has got a clue to the affinities 
and derivation of the«various members of the Sarcode organisms, Rhizopoda. 
The primitive forms, non-nucleated Cytodes, Hackel’s Monera ( Protogenes , 
Protamceba , &c.), Schulze regards as the lower undivided stem. From these, 
by differentiation of a nucleus in their protoplasm, are evolved the nucleated 
forms (Amoeba, freshwater Monothalamia, Foraminifera, Heliozoa, &c.), 
which constitute the subdivisions into which the stem branches off. These 
repeat the various modifications of pseudopodia (Lobose, Filiform, &c.), 
which have already existed in the primitive forms, and which they thus 
derive by inheritance from their non-nucleated progenitors. Finally, through 
the branch of the Heliozoa, we are conducted to the ultimate twigs formed 
by the families of the Radiolaria, in which we find not only nuclei but a 
“ central capsule,” indicating the highest grade attained by any member of 
the group. 
The so-called 11 Colonial Nervous System ” of the Polyzoa. — In 1860, Fritz 
Muller described a series of cords with ganglionic inflations which he had 
found traversing the stem and branches of the polyzoary in Setnalaria Cou- 
tinhii, a polyzoan of the Brazilian coast, and which he regarded as a u colo- 
nial nervous system ” destined to transmit sensations to different parts of 
the common structure, and probably to govern the movements of the zooids. 
Other observers, especially Smitt and Claparede, detected something of the 
same kind in European species of Cheilostomatous Polyzoa, and M. L. Joliet 
has recently communicated to the French Academy of Sciences (“ Comptes 
rendus,” April 9, 1877), the results of his observations on Bowerbankia im- 
bricata , Johnst., a species which, with its congener, B. densa, Farre, is par- 
ticularly well adapted for such investigations. 
The colonial nervous system in Serialaria , as described by Fritz Muller, 
consists of the following parts: — 1. A central cord which traverses the 
length of each joint of the stem, and divides distally into as many branches 
as the joint gives off ramifications; 2. Granular ganglia placed at the bases 
of the branches and of the zooecia, or cells of the individual polypides ; 3. A 
plexus sup eradded to the central cord and uniting the gangliaof the branches 
and zooecia ; 4. A nerve which runs from the ganglion at the base of each 
zocecium to the bud and to the intestine of the adult polypide. All these 
parts are equally distinct in Bowerbankia imbricata , but some of them bear 
a very different interpretation from the above. 
In this species, according to M. Joliet, the central cord consists of large 
fusiform cells, not containing a distinct nucleus, but a very variable number 
of refractive granules. These cells agree with no known nervous element. 
The plexus possesses the same structure as the central cord ; and its branches, 
instead of running to some particular point, or to some organ, such as the 
muscles, generally go to indeterminate points in the walls of the cell where 
there would appear to be no movement to produce or sensation to perceive, 
and here, instead of forming something like an ordinary nervous termination, 
they become confounded with the endocyst. With regard to the ganglia, 
Fritz Muller would appear to have been misled by appearances. According 
to M. Joliet, at the level of the articulations there are diaphragms, which 
have been already noticed by Reichert in Zoobotryon pellucidus, and which cut 
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