INTRODUCTION 3 



the two poUinia tapers into a caudicle (stalk), the end of which is attached to a tiny 

 disc of membrane with a layer of extremely adhesive matter beneath, always kept 

 moist within the pouch of the rostellum. If a pointed pencil is gently pushed into 

 the mouth of the spur, it will be found on withdrawal that the viscid discs adhere to 

 the pencil, and the attached poUinia are drawn neatly out of the anther. They stand 

 erect on the discs at first, but soon begin to move downwards till they point forwards 

 parallel with the pencH. If this pretty experiment succeeds with any flower, you may 

 be quite sure it is an orchid. Exactly the same thing happens when an insect touches 

 the rostellum. Just below the anther is the stigma (J/.), glistening with a sticky 

 secretion, and often bordered by a coloured line. In Text-fig. i it is situated on the 

 inside surface of the roof or back of the chamber forming the spur-entrance, and is 

 shield-shaped, with a violet line on each side. If touched by a poUinium, packets or 

 httle masses of pollen adhere to it so firmly, that they become detached and remain 

 on the stigma. In Cypripedium there are three stigmas, all united into one. In the 

 Monandras there are two, usually also united, the upper stigma having been trans- 

 formed into the rostellum. In some genera, e.g. Gjmnadenia (PI. F, fig. 2), the two 

 stigmas are separate; the column has a lobe on each side of the anther, and a stigma 

 IS situated on the front surface of each of these oval-shaped lobes. 



If the flower is fertilised, the ovary swells, and develops into the seed-capsule. 

 When ripe this opens in fine weather by three longitudinal slits, the valves thus formed 

 remaming jomed both at base and summit. The minute seeds, resembling sawdust 

 m appearance, are shaken out and carried away by the wind. In wet weather the 

 capsule lengthens, and the valves dose up again, till fine weather returns, when the 

 capsule contracts lengthwise, once more opening the valves. 



PI. 3 B shows a much-enlarged column of Cephalanthera grandiflora, with the anther 

 at the summit, and the four half-poUinia leaning forward over the upper edge of 

 the ghstening stigma immediately below it. There is no rosteUum in this genus. 



This work does not go into microscopic detail, but as so much is said nowadays 

 about cliromosomes and their numbers, and their possible use for authoritatively 

 discrimmating between species,' it may be of interest to state what is referred to 

 Herr Pfeiifer-Wellheim's beautiful stereograph in PI. A, fig. 2 (p. 6), shows sLx con- 

 secutive phases m ceU-division taken from the root-tip of Allium cepa L. Beginning 

 at the top, they are as follows : 



I. Spireme. Nucleus breaking up into a tluead from wliich cliromosomes are 

 formed. 



conf rnv.^^r i:'?^ 'PP'/'°' *^' "^"^ '^' ^/^? 2^ *^ chromosome numbers the hitherto undecided 

 ^Trfn^r/. Jf $'\T^^'^^^'^ P°'t"°" °f '^'ff"^"' ^"ie^ ^iU be probably easy to determine." 

 S-1^ / f?J^u K-M. Hoffmann "Beitrage zur Cytologie der Orchidaceen" in Planta, Archiv 



JKru'issensc/Mfihch Bofamk,Bsindx, Heft i, p. ')^}.) 



