

RAM A I. REPETITION*. [iXTROD. 



tion as to what it might be if imperfect. Between the form in -3 

 and tin- form in -4 are intermediates possible? and it' possible, do 

 th.-y exist * Now by choosing suitable species of regular flowers, 

 indiudual flowers may no doubt be found in which there are three 

 l:ir. nents and one small oue ; or two normal segments and a 



third dmded into two, making four in all. Such flowers are firstly 

 \\hile cases of perfect transformation are common. But be- 

 r rarity there is, further, a grave doubt whether they are 

 in anv true sense intermediate between the perfect form in -:> and 

 tin- |.".-rf. ct form in -4. After this again it must be asked whether 



10 th. v do as a matter of fact occur as intercalated steps in the 

 descent of the form in -4 from the form in -3 ? To the last ques- 

 ti..n a general negative may at once be given ; for though there is 

 abundant evidence that Meristic Variations of many kinds arid in 



ial degrees of completeness may be seen in the offspring of the 

 aame parent, yel any one member of such a family group may 

 -li.-w a particular Variation in its perfection, and the occurrence of 

 anv int. im.-diate in the line of Descent is by no means necessary 

 for ill.- production of the perfect Variation. 



'I'., an-u. r the former question, whether or no forms imperfectly 

 ividrd int.. four parts are in reality intermediate between those 

 in -:{ and those in -4, a knowledge of the mechanics of the 

 I in ..-.--. of 1 )i\ i-ion is required. Such knowledge is as yet entirely 

 \\antiir_r. and di-'-ussion of this matter must therefore be prema- 

 tun-. With niu.-h hesitation I have decided to make certain 

 i. tl. xi'.n- .'ii tlh- -ulijert, which will be found in an Appendix to 

 tlii- w.irk. Tli-- may perhaps have a value as suggestions to 

 oth.-r-. though from th.-ir theoretical nature they can find no place 



here. 



Th. ! i- how.-ver an. it h< -r class < if cases which are intermediate 

 in a ditf-n-nt wav. In tin- Tulip described above the quality of 

 divi-i-.n int.. I- WBS piv>.-m in all tin- floral organs. This is not 

 alwavs th. case, tor a M.-ristic Variation may be present in one 

 as, though it is aljsent in -ome or all of the others, 

 and this i- a phenomenon fn-.|ii.-nt ly i-fi-urring. Nevertheless, 

 tli..tiL,di onl\ partially distrilmted, a Variation inav still be dis- 

 |ila\i-d in it-> totality in the parts wherein it is present. The 

 pan- "t a -in-^li- uliorl, the <-al\\ for .-\ainple, may undergo a 

 coiii|.l. t.- N'ariatioii, while the corolla and other parts are un- 

 ehang.-d. In the same \\ay single memlu-rs of a radial series, as a 

 ).. tal for example, may undergo a complete Variation while the 

 oth'-r in. mil. i- of tin- series are unchanged. The same will be 

 -h.'un hen-alt, r t be true of animals also. 



K.'i iii-iaiic.-, the normal number of the parts in the disc of 

 Am-i'liii is four, but the whole liodv ma\ \- divided instead into 



. 



-i\ .T some other number of pans. Examples are also found in 



uliich tin- parts ( ,f one-half or of one quadrant are arranged in the 

 new numli.-r, whd- the remainder is normal; and, as in flowers, 



