242 YOCABtJLARY. 



IRIS. So called from its resembling the rainbow in a variety of 

 colors. A membrane, stretched vertically at the anterior 

 part of the eye, in the midst of the aqueous humor, in which 

 it forms a kind of circular, flat partition, separating the an- 

 terior from the posterior chamber. It is perforated by a cir- 

 cular opening called the pupil, which is constantly varying 

 its dimensions, owing to the contractions of the fibers of the 

 iris. 



ISODAC'TYLE. Hoofed quadrupeds with toes in even number, as 

 two or four, and which have a more or less complicated 

 stomach, with a moderate-sized, simple caecum. Examples: 

 Ox, hog, peccary, hippopotamus. R. Owen. 



Lr. 



LACH'RYMAL. Belonging to the tears. This epithet is given 

 to various parts. 



LACUNAE OF BONE. Certain dark, stellate spots, with thread- 

 like lines radiating from them, seen under a high magnifying 

 power. These were first believed to be solid osseous cor- 

 puscles or cells (corpuscles of Purkinje), but are now re- 

 garded as excavations in the bone, with minute tubes or 

 canalic'uli proceeding from them and communicating with 

 the Haversian canals. The lacunae and canaliculi are fibers 

 concentrated in the transit of nutrient fluid through the osse- 

 ous tissue. 



LAM' IN A. A thin, flat part of a bone; a plate or table, as the 

 cribriform lamina or plate of the ethmoid bone. Lamina and 

 lamella are generally used synonymously, although the latter 

 is properly a diminutive of the former. 



LESIOX. Derangement, disorder ; any morbid change, either in 

 the exercise of functions or in the texture of organs. ' Or- 

 ganic lesion ' is synonymous with organic disease. 



LIPO'MA. A fatty tumor of an encysted or other character. 



LIPOM'ATOUS. Having the nature of lipoma. as a lipomatous 

 mass. 



LIQUOR SANG'UINIS. A term given by Dr. B. Babington to one 

 of the constituents of the blood, the other being the red par- 

 ticles. It is the effused material (called plasma, coagulable 

 or plastic lymph, intercellular fluid, &c.), from which the cells 

 obtain the constituents of the different tissues and secretions. 



