Glossary 



383 



hormone (which see) for them, 

 and has revealed their great im- 

 portance not only for physiology, 

 but for philosophical biology. 



INVOLUTION. Literally inrolling, or 

 inwrapping. In descriptive biol- 

 ogy used to signify the return of 

 an organ to its original or nor- 

 mal condition after some violent 

 or pronounced deformation of it. 

 Sometimes, but apparently un- 

 justifiably, used as a synonym of 

 degeneration. Since the doctrine 

 of evolution has become prom- 

 inent in biology, a process the 

 opposite of evolution has been 

 thought by some to be necessary, 

 and to this involution has been 

 applied. 



JELLY-FISH. In the interest of dis- 

 criminative knowledge, the habit, 

 rather common among people 

 who have the opportunity to see 

 the transparent, somewhat gela- 

 tinous-appearing animals of the 

 ocean, of calling them all "jelly- 

 fishes" should be abandoned. The 

 name should be restricted to the 

 regularly disc- or dome-shaped, 

 tentaculated animals belonging 

 to the coelenterate phylum, thus 

 enlarging the bounds of definite, 

 popular zoological information, 

 by recognizing that marine ani- 

 mals of several large and very 

 distinct classes have this general 

 consistency and appearance. 



KARYOPLASM. A cytological name 

 referring to the substance or 

 plasm distinctive of the cell-nu- 

 cleus. 



KARYOSOME. A small, discrete, 

 rather constant body which 

 stains readily, contained in the 

 cell-nucleus; frequently synony- 

 mous with nucleolus. 



KATABOLISM. The down-breaking, 

 or descensive phase of metabol- 

 ism; the opposite of anabolism 

 (which see). 



KINETO-NTJCLEUS. One of the nu- 

 clei in the two-nuclear protozoa 



supposed to be concerned in 

 some special way with the move- 

 ment of the flagella or cilia of 

 these animals. 



LAMELLAE, singular lamella. A 

 term much used in anatomy to 

 designate the thin plates, scales, 

 etc., that are so numerous and 

 varied in form and size in nearly 

 all organisms. 



LARVA. Properly applied only to 

 stages in the lives of individual 

 animals which pass into succeed- 

 ing stages through a deep-sealed 

 metamorphosis, as for example 

 the grub or maggot of a fly, and 

 its transformation into the adult. 

 Larval stages and profound 

 metamorphoses are very common 

 and widespread in the animal 

 kingdom. 



LIMULUS. The technical genus 

 name for the horse-shoe crab, an 

 animal of special interest to gen- 

 eral zoology in several ways. 



MACRONUCLEUS. In the infusoria, a 

 group of protozoans, there is one 

 large nucleus and one or several 

 much smaller nuclei. The first is 

 called, from its relatively large 

 size, the macro-nucleus; the 

 others micro-nuclei. From the 

 behavior of the two kinds of nu- 

 clei at conjugation and division, 

 the micronuclei are known to be 

 intimately connected with these 

 processes, while the macronucleus 

 seems to be more concerned with 

 the nutritive functions of the 

 animal. 



MAXUBRIUM. In morphology a 

 part or organ which resembles a 

 handle; specially the clapper- 

 like, or handle-like portion of a 

 medusa which is found within 

 the "bell." The animal's mouth 

 is at the end of the manubrium, 

 and most of its digestive cavity 

 within the stalk of the manu- 

 brium. 



MATRIX. In biology the ground 

 substance in which cells are em- 



