534 
Professor Ehrenberg has more recently an- 
nounced that he had detected a nervous fila- 
ment encircling the margin of the dise in one 
of the pulmonigrade Acalephz, and connecting 
the red spots, which he is pleased, as we think 
without sufficient reason, to call eyes, with each 
other. Such a nervous system would, at least, 
be anomalous ; and, notwithstanding the justly 
high reputation of the eminent professor of 
Berlin, we cannot but think that the interests 
of physiology require us to pause before we 
assent to the views of Professor Ehrenberg,as re- 
lates to the nature of the filament in question. 
In the Sterelmintha or parenchymatous En- 
_ _ tozoa of Cuvier, the same acrite condition, both 
of the nervous and muscular systems, is still 
observable in the lower forms belonging to this 
group of internal parasites, which being, for the 
most » in their natural situations either en- 
closed in cells or closely imbedded in the sub- 
Stance of the viscera of other animals, could 
not be expected to have any power of locomo- 
tion conferred upon them; their bodies are, 
therefore, in the simplest species (such as the 
Hydatids, Cysticerci_) mere membranous bags 
of homogeneous texture, and without a trace 
of fibre in their composition: their powers of 
moving are proportionately feeble, and are 
limited in fact to slight contractions, which are 
but indistinctly perceptible on the application 
of stimuli to the surface of the living animal. 
In the Tape-worms ( Tenia) the presence 
either of nerve or muscle is equally impercep- 
tible, and the whole structure strictly conform- 
able to the Acrite type. As, however, we 
mount higher in the scale of organization 
among these parasites, we again find how 
nearly succeeding types of structure are made 
to approximate, and even to a certain extent to 
become blended, as it were, with each other. 
In the Flukes ( Distoma ) and kindred genera, 
and in many of the Acanthocephalous Sterel- 
mintha, although their structure is evidently 
parenchymatous, the skin, without presenting 
any decided appearance of muscular fibre, be- 
comes more coriaceous and contractile, and at 
the same time nervous filaments become dubi- 
ously perceptible : a transition is obviously in 
progress, and thus we are gradually introduced 
to another and a more elevated series of 
animals. 
The NematToneura, as is obvious from 
every part of their economy, are gifted with 
higher attributes, and permitted to enjoy a 
more extended intercourse with external ob- 
jects than any creatures comprehended under 
the preceding division. They are no longer 
rooted to one spot or imprisoned in enclosed 
cavities, but, on the contrary, are for the most 
part erratic in their habits, and in many of them 
the locomotive system is so efficiently con- 
structed that their movements, exhibiting con- 
siderable activity and energy, argue the posses- 
sion of distinct and precise!y arranged muscles, 
searches are well known, that, although they had 
examined several hundred specimens of the Beroe 
in question, for the purpose of ascertaining this im- 
portant fact, their endeavours to detect the nervous 
systzm referred to had been entirely unsuccessful, 
MUSCULAR SYSTEM. 
and display such combination and consentane- 
ous action of different parts of the body ¢o- 
operating to produce a given result, that the 
existence of an intercommunication throughot 
the system by means of nerves might read 
be predicated, even had not anatomy reve: 
to us that such animals actually possess a ner- 
vous apparatus. It would seem indeed to be 
clearly indicated by the physiological relations 
that exist between the two systems, that . 
possession of muscular fibre arranged in dis- — 
tinct fasciculi involves, as a matter of course, 
the co-existence of nervous threads, wh 
the actions of distinct and distant muscles 
be associated for the attainment of a common 
object ; and accordingly we find that these two — 
important additions to the animal eco a 
make their appearance sincera No- 
large ganglionic masses are as yet developed 
sufficient importance to be d as consti- 
tuting a common sensorium, to which the per- 
ceptions derived from external senses must b 
referred, and from whence mandates of volit 
can be supposed to emanate. Senses, th 
fore, that 1s, localized and special senses, can 
not as yet be given; the traces of individuality 
are but feebly recognizable ; the vital power 
are still, to a great extent, diffused throug! 
the different tissues of the body, and not | 
lected and concentrated, as in animals — 
sessed of brains, that is, of centralized — 
dominant aggregations of neurine; and, as 
consequence of this important circumstane 
some of the most striking characters commo 
to the Zoornyres still linger in this divisi 
of creation ; the radiated form is yet extensive 
met with, multiplication by mechanical div 
sion of the body is still, to a certain ext 
possible, and severed portions of the body 4 
found to be reproduced by growth from t 
mutilated part. : 
The C@LeELMINTHA or Cavi 
worms, living in the interior of other anit 
differ in so many points from the Acrite Ento; 
that Cuvier, although in the Regne Anima 
was content to group them together in the: 
class, was obliged to separate ‘hem into _ 
distinct orders, calling the SrerELMIN' 
“ intestinaux parenchymateux,” while the f 
highly organized are designated “ intestin 
cavitaires.” The Ceelelmintha, in fact, are 
ganized in accordance with quite a diff 
type of structure, as must be at once ev! 
upon the slightest comparison between 1 
The digestive apparatus is now no longer 
posed of tubes excavated out of the § 
mass of the body, and presenting no outt 
the escape of egesta, but a distinct alim 
canal now makes its appearance, suspen 
a capacious abdominal cavity, wherein, 
over, are lodged the male and femal 
generation, which in the Celelmintha are 
rally found in different individuals. The 
rietes of the body are in these worms obv: 
muscular, and are composed of © 
fibres arranged in superposed strata and @ 
ing different directions. Towards the ext 
of the body they are disposed longitudina 
but the inner layers assume a circular or spi 
> 
i: 
id 
ensive 
