98 Reviews and Records in Anatomy and Physiology. 
As to the minute structure of the non-striated muscular tissue, 
we have but little to say. We have found it uniform and the 
same wherever occurring, even when it has the futiction of vol- 
untary tissue, as is the case in the Mollusca and Radiata. 
been stated by Lebert and Robin to be the case in some of the 
Cephalophora* ; on the other hand, in many species of this class, 
which have been examined we have found this tissue to be com- 
posed of fibres which admit of no further division except into 
their constituent cells. 
Less studied, but at the same time more interesting, histologi- 
cally, is that form -of this tissue, which persists permanently on 
the cell-type, the cells still preserving their characteristics as such, 
instead of being lost in their contribution to a distinct form of 
tissue. This form of tissue composes the mass of muscle of the 
Radiata proper, and is perhaps best observed in the Acalephee, and 
Polypi. Agassiz has given it a good description, as occurring 10 
the former of these classes,t and in the latter we have frequently 
observed it, while making other investigations. A very fine 
example of this cell-muscle may be observed in the pedicle of 
the medusa-form of Tubularia: here, a double row of cells is 
observed ;—these last, when in a state of relaxation are round or 
ovoid, but when contracted they wear a flattened, dise-like form, 
ak c 
the physiologist than the observation of such phenomena, for 
nature is here observed with just that amount of drapery which 
would hide yet adorn her nakedness. 
Before closing these remarks on the histological composition of 
muscle, we wish to refer to another point, in the form of an 
q : 
than that of being composed of cells? This query is advanced, 
becatise in some instances of the locomotive, contractile, if not 
muscular tissue of the lower animals, we have not succeeded in 
making out any cell-structure. This has been the case with the 
otherwise muscular, and highly contractile parts of some of the 
lower Helminthes, where the tissue in question seemed resolvable 
into granules alone, allocated under distinct forms by a delicate 
* See, Kurze Notiz fiber allgemeine vergleichende Anatomie niederer Thiere, in 
Miiller’s Arch., 1846, p. 120. 
See Contributions to the Natural History of the Acalephz of North America, 
in the Memoirs Amer. Acad. Arts and Sci, 1850, N. S,, iv, P. H, p. 239. - 
