392 

by measure, The amount of organic matter in soils, when 
compared with the amount, weight for weight in the water 
at the same stations is from 10 to 20 times greater ; one in- 
stance is given in which it was 4o times greater. But the 
most interesting scientific facts are those connected with 
the development of lower forms of life in infusions of soils 
in water. Besides a few a/ge@, the prevailing forms are— 
Monas lens, Paramecium, Monera assuming the most 
fantastic outlines, Vébriones, dmaba, Englene, &c. 
We look forward with great interest to further instal- 
ments of this important inquiry, which we trust may add 
largely to eur knowledge, and by this means enable human 
life to be saved. 


FOSSIL CETACEA 
(EE SNS the recent extensions of the fortifications of 
Antwerp, which have occupied some years, very 
fine opportunities have been offered, as is well known to 
geologists, for studying the Crag formations (Diestien 
and Scaldisien systems) of Antwerp, of which we have 
remnants on our own east coast. It is not. however, so 
well known that the Belgian Government during the exca- 
vations used every care to preserve the remains of Cetacea 
and other marine mammalia thus disinterred. The 
workmen were instructed to give up all such remains for 
the Government, and were not allowed to sell them. 
Parts of the Black and Grey Crags proved to be a com- 
plete charnel house—so abundant were the remains—and 
these have been quietly brought together and placed 
under lock and key for the last eight years. The richness 
of the fauna disinterred may be judged from the fact that 
it is stated that eight new genera of Ziphioid. Cetaceans 
are indicated besides sixteen new species belonging to 
known genera. Many of the forms are represented by 
far more complete portions of the skull than have hitherto 
been known from these beds, also portions of the trunk, 
limbs, and lower jaw in connection with these. Portions 
of the skull of the fossil Walrus, tusks of which occur in 
the Suffolk bone-bed and have been described as Triche- 
codon, have been obtained, as well as remains of seals. 
All these specimens are under study by the Vicomte du 
Bus, and are not open to the inspection of even profes- 
sional paleontologists. They are being carefully and 
freely engraved, and will soon, it may be hoped, be made 
known to the world, 



PARASITES 
ROF. VON BENEDEN, as we have before 
noticed, has distinguished true parasites, which live 
on their host, from commensals, those which live merely 
with their host, the thieving impostor from the respectable 
lodger. In an admirable work on the “ Fishes of the 
coasts of Belgium, their Commensals and Parasites,” 
published by the Academy of Sciences of Brussels, he 
now further classifies parasitic organisms. The com- 
mensals are either 1, Ozkoszfes, fixed ; or 2, Coino:ttes, 
free. The Oikosites fish for their own living, and merely 
ask a free passage from their hosts. They are either fixed 
in perpetuity, as Covonula, Cochliolepis, Modiolaria, 
Mnestra, and Loxosoma, temporarily as the Remora, 
Anilocra, Praniza, or only in the young state, e.g., Calzgus 
and Avodon. The Coinosites, on the other hand, never 
give up their liberty ; they occasionally leave their host, 
and between Coinosite and host there is often an exchange 
of good offices, one furnishing a solid house or a strong 
claw, the other a sharp eye, and they may share their 
prey in common. The digestive canal is occupied by 
thefollowing Coinosites :—Fverasper, Stegophyle, Stylifer, 
Phronimus, Hyperia, the mantle by Pinnotherus and 
Pagurus, the exterior by A/yzostoma, Cyamus, Pycnogonon 
Caprella, and Chetogaster, 
NATURE 


[March 16, 1871 
The true parasites cannot live without assistance, they 
are divisible into several categories. Some, such as the 
leech, fleas, and some dipterous insects, suck the blood of 
their victim, and then quit him to take their after-dinner 
nap in the open air; others, such as the ichneumon flies, 
do not quit their host till they have become adult, and 
have in the process exhausted the last drop of blood of 
their unfortunate prey. The greater number lead a free 
life when young, and merely attach themselves to a host 
at the time of reproduction, such are the Bopyrian and 
Lernzean Crustacea. There isa further very interesting 
group, who enter a host while yet young, simply in order 
that they may get carried by its means into a second 
host, where they will ripen their eggs. Often whilst wait- 
ing in their first host (sometimes vainly waiting no doubt) 
for him to be devoured by their second and ultimate 
victim they reproduce agamically. Such parasites are 
the Flukes and many Tapeworms. These divisions are 
thus tabularly set forth :— 
Parasites free 

during all their life. during a part of their life they pass through 


——— —_————— — 
Leeches. a single host. several hosts whilst immature. 
Fleas and Flies. —____— —- 
Caliga. whilst im- when ma- Distomata. 
mature. ture. Cestoids. 
Ichneumons. Bopyrians. 
Mermis. Lernzeans. 
The parasites of the first category which are free during 
all their life, Professor Van Beneden calls Phagosites, and 
compares them to the #aditués of a hotel who avail them- 
selves of the ¢adle d’héte, but do not have a bedroom in 
the building. The other parasites which have both board 
and lodging are divisible into three principal categories. 
ist. Xenosites—who are pilgrims in transit—voyaging 
with a distinct but distant object in view. They are always 
agamic, lodge in such closed organs as the brain, muscles, 
and serous membranes, and wait patiently till they get 
into the stomach of the animal where they are destined to 
breed. The stomachs and appendages of fishes swarm 
with parasites, and those which have the largest clientéle 
are by no means the least healthy or thinnest. Often one 
fish, having swallowed another, is swallowed by a third, 
and thus Xenosites find themselves set free in the wrong 
fish’s stomach, for the stomach acts like a filter, straining 
out and retaining the parasites, while the flesh is digested. 
Such erring Xenosites merely wait, and may often pass 
through several “hotels” before they reach their destina- 
tion. 2nd. Nostosites—those who have reached their 
destination, and now can abandon themselves to genera- 
tion. Whilst the Xenosite was obliged to put up often 
with an uncomfortable cramped lodging, biding his time, 
the Nostosite occupies the most eligible organs for para- 
sitism—in fact, the most vast and commodious chambers 
of the hotel. The 3rd division are the Pilgrims, who 
have lost their way hopelessly, and are in worse plight 
than even in Giant Despair’s castle. Such are the agamic 
worms which are found often in the Plagiostomous fishes, 
and who ought to have got into some Teleostean fish, 
there to fructify—a happy fate for ever lost to them when 
by unlucky chance the host in whom they trusted was 
swallowed by a remorseless shark. They never quit this 
retreat 
Professor Van Beneden gives directions for searching 
an animal for its parasites, and justly claims a high interest 
for the study of the fauna of individual species, and urges 
such neat and sharply-limited zoological inquiries on those 
who do not feel prepared to study the fauna of a geo- 
graphical region—to the philosophy of which, indeed, the 
study of parasite-faunze may furnish important sugges- 
tions. Ninety-three species of fish, with their parasites — 
and commensals, are cited in this work trom the author's 
own observation, Eight plates illustrate it. 
ER 
