Involute 



A DICTIONARY 



Joint 



iN'VOLfJTE, rolled inward from 

 both sides. Compare Con- 

 volute. 



INV0LUTI0N-F6RM, a swollen 

 bladder-like form in Scbizo- 

 niycetes, supposed to be a dis- 

 eased condition of the form 

 with which it "is found asso- 

 ciated. (De Bary.) 



lNV6LtT'TI0N-PE'Rl6D,seeREST- 



ING-PERIOD. 



lNV0LtJ'TI0N-STA6E, see Rest- 



ING-STAGE. 



IRREGULAR, denoting flowers 

 in which one or more of the 

 organs of a set are different 

 in size or form from the 

 others. Irregularity occurs 

 most frequently in the petals. 

 The pea is an example of au 

 irregular flower, the tulip of 

 a regular. Compare Symmet- 

 rical. 



Irregular pelor! A, a tera- 



tological condition in which an 

 irregular flower becomes regu- 

 lar by the formation of tbe 

 irregular parts in increased 

 number. Compare Regular 

 Peloria. 



IRRITABILITY, having the 

 power of movement in a 

 definite mauner under the 

 influence of external stimuli, 

 as in the coiling of tendrils, 

 twining of stems, or "sleep" 

 of leaves; sensitiveness. Com- 

 pare Excitability and Con- 

 tractility. 



ISAdEL'PHOUS, having an equal 

 number of stamens in each 

 adelphia. 



^BILATERAL, having two 

 sides alike in form and struc- 

 ture, as the leaves in the iris. 



ISOB'RiOUS, applied to the em- 

 bryo of dicotyledons because 

 both are equally developed; 

 isodynamous. Little used, 



ISO€HRO'US, uniform in color 

 throughout; uuicolor. Com- 

 pare Concolor. 



ISODY'NAmoUS, equally devel- 

 oped. 



ISdG'AMY, the conjugation of 

 gametes of similar form. 

 Compare Oogamy. 



Is6G YNOUS, having the pistils 

 of a flower all alike. Compare 

 Heterogynous. 



ISOMER'IC, see Isomerous. 



ISdM'EROUS, having the same 

 number of organs in each 

 floral whorl; isomeric. There 

 may be more than one whorl 

 of any of the kinds of organs. 

 Compare Heteromerous. 



ISdPH'OROUS, transformable into 

 something else, as "Actinia is 

 an isophorous form of Dendro- 

 bium." 



I'SOSPORE, said of a spore when 

 all are alike, as in ferns. (Rare. ) 

 Compare Macrospore and 

 Microspore. 



ISdS'POROUS, not having macro- 

 spores and microspores; ho- 

 mosporous. Compare Heter- 

 osporous. 



ISOSTflM'ONOUS, having the sta- 

 mens equal in number to the 

 petals. More properly, having 

 the stamens and petals each in 

 one whorl and of equal number. 

 Compare Anisostemonous, 

 Meiostemonous, Diplostem- 

 onou8, and Obdiplostemo- 

 nous. 



IS&ST5M0US, having calyx and 

 corolla of equal size. (Rare.) 



ISTH'MUS, the constricted por- 

 tion between the two half-cells 

 in most desmids. 



JOINT, a node; the septum be- 

 tween two cells in a filament; 

 articulation. 



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