March 1, 1894.] Supplement to the " Tropical Agnculturut" 
641 
lu order to make this matter plain to the average 
reader we would say that after every rain the 
soil is settled down, tlie particles of earth are 
packed nearer together, and the spaces between 
them are small. A number of these small space.s 
joined together make little tubes, called "capillary 
tubes," and in these water will rise from below. 
If the soil has not been disturbed after a rain these 
tubes come to the surface, and so does the water 
in them. The water coming to the surface eva- 
porates and escapes, consequently is lost as far 
as that individual crop is concerned. When the 
soil has been ploughed the spaces or tubes are 
made larger, and water will not rise in large tubes. 
Hence it comes up as far as the small tubes are 
undisturbed and stops there, and the loose soil 
above prevents its rapid evaporation. In this 
way and by these means the natural pores of the 
earth are closed; the loose dirt serves as a "mulch," 
and the soil moisture is conserved in time of 
drought and retained in the soil ^exactly where it 
is needed) from one rain to the next. This mulch 
not only prevents the escape of soil moisture, 
but it also tends to check the intense heat of the 
sun in its downward progress to the roots of 
plants. Both of these are very important matters 
during spells of long continued hot, dry weather. 
ZOOLOGICAL NOTES FOE AGRICULTURAL 
STUDENTS. 
The five sub-kingdoms which have now been 
considered, viz.. Protozoa, Ccelenterata, Echino- 
dermata, Annulosa and Molusca, are commonly 
grouped together under the name of invertebrata 
or invertebrate animals. There now only remains 
the sixth and last as well as the highest sub- 
kingdom, that of the vertebra t a or vertebrate 
animals. 
Sub-kingdom VI. Vebtebbat.v. — The name of 
this sub-kingdom is derived from the general, 
though not universal, presence of t he bony stem 
known as the vertebral column, spine or backbone. 
In its most complete form the vertebral column 
consist.s of a number of separate bony segments or 
vertebraj, arranged so as to form a bony axis upon 
which the part of the nervous system called the 
spinal cord is supported. In some cases the 
vertebral column is partially bony or permanently 
cartilagenous, or again is replaced by a uotochord 
" a peculiar gristly or gelatinous rodlike struc- 
ture, consisting of cells enclosed in a libi'ou* 
sheath." 
Characteristics. -Body comjjosed of a uum- 
l)er of deiiiiite segments placed one behind the 
other in a longitudinal series. The main masses 
of the nervous system are placed upon the dorsal 
aspect of the body and one cut off from the 
general body cavity. The limbs, when present, 
are turned away from that piirt of tliebody on 
which the nniiu masses of the nervous system are 
placed, and aro never more than four in number. 
In most case-, ii backbone or vertebral column is 
present in I'lilly-yrown animals. 
Class 1. Pisces, compriae the lishes which 
form the lowest class of vertebrata. Respiration 
in them is caiTiod on by means of gills placed on 
eitlu'v .side of tlif nni k of I he li.-li. W ili" i> nrl- 
mitted by the inotii b by means ot ii series of | 
fissures in the throat, and after passing over the 
gills, it mak<»=! its escape by a single opening on 
the side of the neck called the gill-slit, Which 
is covered over by a kind of folding door called 
the gill-cover. The heart usually consists of 
one auricle and one ventricle. The blood is cold, 
and thelimbswhen present are in the form of fins. 
As members of this class we may mention the 
shark, herring and eel. Under it are included 
all salt-water, fresh-water, and mud fish. 
Class II. Amphibia. Among the amphibians 
(animals living both in land and in water) respi- 
ration is carried on at first exclusively by means 
of gills, afterwards by lungs, alone or associated 
vvith gills. The skull has two condyles, the 
limbs never occur as fins, and the heart of the 
adult consists of two auricles and one ventricle. 
The common amphibians are the frogs, toads and 
newts. In the true frog the upper jaw always 
carries teeth, and there is a tongue, like that of the 
.toad, fixed to the front of the mouth and free 
behind, which it can protrude at will. The typical 
frog has enormously-developed hind legs, the 
toes of which are united by membrane or are 
webbed ; they swim very powerfully and can 
take extensive leaps. The tree frog is adapted 
for climbing trees, which it does by the 
help of suckers developed on the ends of all 
the toes. The fishes and amphibians are classed 
togetlmr as I chthyopsida. 
INDIAN JOTTINGS. 
An interesting correspondence was recently 
published in the Bombay paper's in the form 
of a report to the Bombay Municipality 
from its Health Officer, Dr. Weir, regard- 
ing the connection between epizootics and 
epidemics. Rinderpest and foot and moutli 
disease broke out in Bombay early this year. 
The Health Officer points out that these animal 
plagues are generally followed by luiman plagues, 
inasmuch as the air is infected with diseased 
germs. This, it appears, is not the first 
time Dr. Weir drew attention to the subject, 
for it is said that years ago even when Veteri- 
nary experts were doubtful regarding the true 
nature of rinderpest, he fought single-handed 
and took steps to prevent the spread of 
animal plagues solely with a view to prevent- 
ing the outbreaks of human maladies. Besides, 
from that time, that is since 1874, he has carefully 
studied the subject and collected all available 
evidence on it and hence now speaks authori- 
tatively. This throws a new light on the 
question of animal diseases. They are bad in 
themselves in causing material loss to the people, 
depriving them of their supply of meat and milk 
and the labour of the animals in the cultivation 
of the soil and tlie carting away of the produce. 
The agricultural labourer is the firat to suffer 
from these causes, and oftentimes it happens 
that the wealthier classes, who are capable of 
devisiii!.; mi'asures for the prevention or suppres- 
sion of these diseases are seldom aftVcted, and 
hence rarely take a lively interest in the subject, 
particularly as tliey are unaware of the suff^^r- 
i'i<T and lo-ss the poorer classes uuderj^o on this 
tici-oiuii. But vheu it i? ik>w kuowu thai 
