lactocrite 
and used in creameries in connection with his 
centrifugal separator. A mixture of the milk to be 
tested with an equal volume of a mixture of 95 parts of 
strong acetic acid and 5 parts of strong sulphuric acid 
is heated for eight minutes in a glass or porcelain vessel. 
This process sets free the fatty substance of the milk, 
which, however, still remains diffused throughout the 
mass. The lactocrite is a long narrow-necked tube, fitted 
to a holder on a disk attached to the centrifugal separator. 
The prepared milk is placed in this tube, and the rotation 
of the centrifugal separator acts, as in the separation of 
cream from milk, to aggregate the fat in the narrow neck 
of the tube, when its quantity can be determined by a 
scale. When all the steps of the process are performed 
with exactness, the value of the sample for butter-making 
can be determined with an average error of only one twen- 
tieth of one per cent. 
lactodensimeter (lak // to-den-sim'e-ter), n. [< 
L. lac(t-), milk, + denstis, thick, dense, + Gr. 
fierpov, a measure.] A kind of lactometer fur- 
nished with scales intended to show what pro- 
portion of the cream, it' any, has been removed 
from a sample of milk by skimming. 
lactometer (lak-tom'e-ter), n. [= F. lactometre 
= Sp. lactdmetro = Pg. lactometro, < L. lac(t-), 
milk, + Gr. jiirpov, a measure.] An instrument 
for gaging the purity or richness of samples of 
milk. Specifically (o) An instrument used in measur- 
ing the volume of cream in a sample of milk, and the 
probable amount of water, if any, which has been added 
to it. The simplest form is a graduated glass tube for 
measuring the amount of cream that rises from a sample 
of milk placed in it. A more complete instrument con- 
sists of a series of tubes each with a stop-cock at the bot- 
tom, arranged vertically in a suitable stand. The tubes 
are about an inch in diameter and 12 inches high, and are 
graduated to tenths of inches. The samples of milk to 
be tested are poured into separate tubes to a depth of 10 
inches. The stand is then set aside and the cream allowed 
to rise. The thickness of the stratum of cream which rises 
is measured in tenths of an inch, or (as the depth is 10 
inches) in huudredths of the volume tested. The separated 
milk is then drawn otf through the stop-cock for further 
tests of richness in caseous matter, etc. (b) A kind of 
hydrometer for testing milk by its specific gravity : also 
called galactometer to distinguish it from the preceding, 
in connection with which it is commonly used. When 
this is called lactometer, the other instrument receives a 
different name, as ereanunneter (Encyc. Brit.), or per cent, 
tube (E. H. Knight). See hydrometer, and cut under go- 
lactometer, (c) Same as lactodensimeter. 
lactone (lak'ton), n. [<L.tac(i-),milk,+ -owe.] 
A colorless volatile liquid possessing an aro- 
matic smell, produced, along with lactide, by 
the dry distillation of lactic acid. 
lactophosphate (lak-to-fos'fat), . [< lact(ic) 
+ phosphate.] A phosphate combined with lac- 
tic acid. 
lactoscope (lak'to-skop), n. [< L. lac(t-), milk, 
+ Gr. aianrelv, see.] An instrument for testing 
the quality and richness of samples of milk, by 
their comparative opacity, constructed and 
operated upon the principle that the richer the 
milk is in fatty and caseous substances the 
greater will be its resistance to the passage of 
light through a stratum of any giyen thickness. 
The samples are tested by alight of equal intensity, usually 
the flame of a stearin candle. A common form of lactoscope 
may be described as a box with two vertical parallel and 
polished glass sides, one of which may be moved by a 
screw toward or away from, and always in parallel rela- 
tion with, the other. The candle is placed at a specified 
distance from the fixed glass side of the box, and as the 
movable side recedes the stratum of milk increases in 
thickness to a point at which the candle-flame becomes 
invisible through it. The various thicknesses at which 
this occurs in different samples are indications of the rich- 
ness of the samples, provided no adulteration other than 
watering has been attempted. There are also lactoscopes 
of simpler construction and operation. (Encyc. Brit.) 
lactose (lak'tos). . [< L. lac(t-), milk, + -ose.] 
Sugar of milk, Cigl^On, obtained by evapo- 
rating whey, filtering through animal charcoal, 
and crystallizing, it forms hard, white, semi-trans- 
parent trimetric crystals, which are less soluble than cane- 
or grape-sugar, have a slightly sweet taste, and grate be- 
tween the teeth. It is dextrogyrate, and ferments slowly 
with yeast, but readily undergoes the lactic fermentation. 
It is convertible into glucose and galactose by boiling with 
dilute sulphuric acid. It is used for food and in medicine, 
and is prepared as an article of commerce in Switzerland 
and Bavaria. Also called galactine, lacttne, and milk-sugar. 
lactosuria (lak-to-su'ri-a), n. [NL., < B. lactose 
+ Gr. ovpov, urine.] The presence of lactose 
in the urine. 
Lactuca (lak-tu'ka), n. [L., lettuce, > ult. E. 
lettuce, q. v.] A "genus of liguliflorous com- 
posite plants, to which the lettuce belongs, 
type of the subtribe Lactucece of the tribe Ci- 
choriacea:, characterized botanically by a beak- 
ed achene and a pappus of delicate and copious 
bristles in many series. These plants are herbs with 
milky juice, usually with both radical and cauline leaves, 
which are generally more or less deeply cut, lobed, or pin- 
natifid, often with bristly ciliate margins, the cauline com- 
monly with clasping or auriculate base. About 65 well- 
authenticated species are known, indigenous in Europe, 
Asia, Africa, and North America. The garden-lettuce, L. 
saliva,, is scarcely known except in cultivation, but is sup- 
posed to be a native of Asia. (See lettuce.) From the Eu- 
ropean species L. virosa principally is obtained the seda- 
3326 
live known as lactucarium, or lettuce-opium. The species 
of this genus all possess narcotic and sedative properties. 
lactucarium (lak-tu-ka'ri-um), n. [NL., < L. 
laetuca, lettuce : see Lactuca.'] A drug consist- 
ing of the inspissated milky juice of several 
species of Lactuca. The species are L. virosa, L. Scari- 
ola, L. sagittate (altimma), and L. sativa, the garden-let- 
tuce. It is regarded as possessing (in an inferior degree) 
the properties of opium, and can be safely used where the 
latter cannot; but it is uncertain in action. It is pro- 
duced in some quantity in several European countries. 
Lactuceae (lak-tu'se-e), n. pi. [NL. (Lessing, 
1832), < Lactuca + -ece.] A subtribe of compo- 
site plants of the tribe Ciclioriacece, of which the 
genus Lactuca is the type. It embraces 10 other 
genera, including Pyrrhopappus, Prenanthes, and Son- 
chus. They are chiefly glabrous herbs with beaked ache- 
ilia and copious bristly pappus. Also written Lactucacece. 
lactucic (lak-tu'sik), a. [< L. laetuca + -ic.] 
Pertaining to plants of the genus Lactuca. 
lacuna (1%-ku'na), n. ; pi. lacuna! (-ne). [Also 
rarely lac'une (<F.) ; = F. lacune = Sp. lacuna, 
laguna = Pg. lacuna = It. lacuna, laguna, a 
pool, marsh, lake, gap, < L. lacuna, a pit, ditch, 
pond, hole, hollow, cavity, < lacus, a basin, 
cistern, lake : see lake 1 . Cf. lagoon, a doublet 
of lacuna.] 1. A pit or hollow. Specifically (a) 
In bot.: (1) One of the small hollows or pits on the upper 
surface of the thallus of lichens. (2) A name given occa- 
sionally to an internal organ, commonly called an air- 
cell, lying in the midst of the cellular tissue of plants. (&) 
In anat., a small pit or depression ; a blind alley or cul-de- 
sac, as one of a multitude of follicles iu the mucous mem- 
brane of the urethra ; especially, a cavity in bone. See be- 
low. (c) In zbol., one of the spaces left among the tissues of 
the lower animals which serve in place of vessels for the 
circulation of the fluids of the body. 
2. A gap; a hiatus; especially, a vacancy 
caused by the omission, loss, or obliteration of 
something necessary to continuity or complete- 
ness. 3. [cop.] In conch., the typical genus of 
Lacunidtt. L. vincta is a common New England spe- 
cies. This small shell resembles a periwinkle, but is thin- 
ner and of slenderer form ; it is of a reddish or brownish 
horn-color, with two or more darker spiral bands. It is 
found on the sea-shore, where the animal feeds on algals. 
Lacunae of bone, the microscopic cavities in the bone 
occupied by the bone-cells, and communicating with one 
another and with the Haversian canals and surfaces of the 
bone through the canaliculi. See cut and quotation under 
bone. Lacunsa of Howship, the foveolse of Howship, 
minute pits in the border of bone undergoing absorption. 
They are excavated by the osteoclasts lying in them. 
lacunal (la-ku'nal), a. [= It. lacunale; as la- 
cuna + -al.] Same as lacunar 2 . 
lacunar 1 (la-ku'nar), n.', pi. lacunars, lacunaria 
(-narz, lak-a-na'ri-a). [L., a wainscoted or pan- 
eled ceiling, so 
called from the j^.--; " **** - ~ - 
sunken or hol- 
lowed compart- 
ments, < lacuna, 
a pit, hollow : 
see lacuna.'] 1. 
One of the cof- 
fers or sunk 
compartments 
in ceilings or 
soffits formed of 
beams crossing 
one another, or 
resembling in 
structural form 
or for purposes 
of decoration such a construction of beams, as 
the stone ceilings of the Grecian Doric, those 
(generally formed of wood and plaster, and 
profusely decorated with gilding and ornament) 
common in Renaissance buildings, etc. 
The lacunaria, or recesses of the roof [in the Ionic order], 
were also certainly painted. 
J. Fergusson, Hist. Arch., I. 253. 
Hence 2. A ceiling or soffit having lacunars. 
lacunar 2 (la-ku'niir), a. [< lacuna + -atf. Cf. 
lacunar 1 , n'., an older form.] 1. Of or pertain- 
ing to a lacuna. 2. Having lacunee ; lacunose. 
Also lacunal. 
lacunaria, . Latin plural of lacunar 1 . 
lacunary (lak'u-na-ri), a. [< lacuna + -ary.] 
Pertaining to a lacuna Lacunary function, a 
function having a lacunary space. Lacunary space, in 
the theory of functions, an area in a plane every point of 
which is the affix of a value of the variable for which a 
given function has no determinate values. Thus, if 
xi yi z* 
Lacunars. From vaulting of Basilica of 
Constantino, Rome. 
then the space within the triangle whose vertices are the 
affixes of a, b, and c is a lacunary space. 
lacune (la-kun'), n. [< F. lacune, < L. lacuna, 
a pit, hollow: see lacuna.] A lacuna; a small 
empty space; agap; ahiatus; a defect. [Rare.] 
A little wit, or, as that is not always at hand, a little 
impudence instead of it, throws its rampant briar over 
dry lacunei. Landor. 
lad 
lacunette (lak-u-nef), n. [< F. lacvnette, dim. 
of lacune, a chasm : see lacuna.] In fort., a 
small foss or ditch. 
lacunid (lak'u-nid), n. Any member of the La- 
cunidce. 
Lacunidse (la-ku'ui-de), n. pi. [NL.,<iocwa,3, 
+ -idee.] A family of tsenioglossate gastropods, 
typified by the genus Lacuna, with shells re- 
sembling those of peri winkles (Littorinidce), but 
having a lacuna in the columella. There is no si- 
phonal fold, and behind the operculum are two processes, 
as in Rissoa. The family is usually included in the Lilto- 
rinidce. 
lacunose (la-ku'nos), a. [= Sp. lacunoso, lagu- 
noso = Pg. It. lacunoso, < L. lacunosus, full of hol- 
lows, holes, ponds, etc., < lacuna, a pit, a hol- 
low : see lacuna.] Having or full of lacunae ; 
furrowed or pitted ; marked by gaps, cavities, 
or depressions; specifically, in hot. and entom., 
having scattered, irregular, broadish, but shal- 
low excavations, as a surface. A lacuuose leaf has 
the venation salient beneath, leaving the surface full of 
hollows. The pronota and elytra of many beetles are la- 
cunose. Also tacunous. 
lacunosorugose (lak-u-no-so-ro'gos), a. [< la- 
cunose + rugose.] In bot., marked by deep, 
broad, irregular wrinkles, as the shell of the 
walnut or the stone of the peach. 
lacunous (la-ku'nus), a. Same as lacunose. 
lacunulose (la-ku ' nu-lds), a. [Dim. of lacu- 
nose.] In bot., diminutively lacunose. Tucker- 
man, North American Lichens, I. 61. 
lacus (la'kus), n. [NL. use of L. lacus, a basin, 
lake: see lake 1 .] 1. In anat., a place likened to 
alake. 2. [cap.] In zool., a genus of beetles of 
the family Eucnemida;. The sole species is L. 
laticornis of Brazil. Bonvouloir, 1870 Lacus 
lacrymalis, the lake of tears, the oval space between 
the eyelids at the inner corner of the eye, occupied by the 
caruncula lacrymalis. 
lacustral (la-kus'tral), a. [< L. as if "lacustris, 
of a lake (see lacustrine), + -al.] Same as lacus- 
trine. 
lacustrian (la-kus'tri-an), a. and n. [< L. as 
if *lacustris, of a lake (see lacustrine), + -an.] 
1. a. Same as lacustrine. 
H. n. A lake-dweller; one whose habitation 
is built upon a lake. 
Not the slightest clew appears as to the manner in which 
the lacustrians disposed of their dead. Amer. Cyc., X. 112. 
Lacustridas (la-kus'tri-de), n. pi. [NL., < *la- 
eustris, of a lake (see lacustrine), + -ida:.] A so- 
called family of fresh-water sponges, including 
those forms of the genus Spongilla which inhab- 
it lakes, as distinguished from the Fluviatilidw. 
Though named as a family, the group has not the taxo- 
nomic value of a genus, and its name is not based upon 
that of any genus. 
lacustrine (la-kus'trin), a. [< L. as if "lactis- 
tris (> It. Pg. Sp. F. lacustre), of a lake, < lacus, a 
lake: see lake 1 .] 1. Of or pertaining to a lake 
or to lakes. 2. Living on or in lakes, as various 
animals. 3. In bot., growing in lakes or ponds. 
Also lacustral and lacustrian. 
Lacustrine deposits, deposits formed at the bottom of 
lakes, which frequently consist of a series of strata dis- 
posed with great regularity one above another. From the 
study of these numerous fresh-water deposits geologists 
obtain a knowledge of the ancient condition of the land. 
Lacustrine dwelling or habitation. Same as lake- 
dwelling. 
lac-work (lak'werk), n. Japanese lacquer. 
lacy (la'si), a. [<.lace + -y 1 .] Resembling lace ; 
lace-like. 
The skeleton f of the Hexactinellidce] comes out a lovely 
lacy structure of the clearest glass. 
Sir C. W. Thomson, Depths of the Sea, p. 418. 
How exquisite she looked in her pale-tinted dress, with 
a lacey shawl wound carelessly around her head and 
shoulders. The Century, XXXVI. 197. 
lad 1 (lad), n. [< ME. ladde, prob. < Ir. lath, a 
youth, a champion, = W. llawd, a youth. It 
cannot be the same as ME. lede, < AS. leod, a 
man: see lede%. For the connection of the 
senses 'boy' and ' servant,' cf. boy 1 and knave 
in like uses. Cf. Ions 1 .] 1. A boy; a youth; a 
stripling: often used familiarly or affectionate- 
ly in speaking of or to a man of any age. 
The ladde whome long I lovd so deare 
Nowe loves a lasse that all his love doth scorne. 
Spenser, Shep. Cal., April. 
Joseph, being seventeen years old, was feeding the 
flock with his brethren ; and the lad was with the sons of 
Bilhah. Gen. xxxvii. -2. 
The ruffling Northern lads, and the stout Welshmen try'd 
it. Drayton, Polyolbion, xxii. 1069. 
How now, old lad? Shak., T. of the S., iv. 1. 113. 
2. A male sweetheart : correlative to lass. 
[Scotch.] 
Ye royal lasses dainty, 
Heav'n iiiak' ye guid as weel as braw, 
An' gie you lads a-plenty. Burns, A Dream. 
