62 



THE GABDENER'S ASSISTANT. 



of any large orchid, such as a Cattleya, Lycaste, 

 or Odontoglossum, you will not see any anthers 

 in the centre of the flower as in ordinary flowers. 

 What you will find in the centre is a wax-like 

 or fleshy column, above the lip, and at its apex 

 you will see a little lid or cap, called the anther- 

 case; and if you lift this cap off gently with a 

 sharp-pointed pin or a knife you will observe the 

 golden-yellow pollen masses ensconced under- 

 neath the cap, before it falls away. 



Our sketch (fig. 79) shows the column of an 

 orchid (Cattleya) enlarged — A is the column in 



Ffe. "9. -a. Front and side view of the column of Cattleya flower, b, Anther- 

 cap, or pollen-case, c, Pollen-masses removed from anther-cap. u, Pol- 

 Ien-mas8e8 on tip of bamboo-pointer, ready for applying to the viscid 

 Stigmatic surface, as shown by dotted arrow. Figures marked thus X 

 are slightly enlarged. 



its entirety, B is the anther-cap at its apex; at C 

 are the pollen-masses (to be removed on a tooth- 

 pick), and at F you may see the stigmatic cavity 

 or glutinous surface on which the pollen-masses 

 must be placed in order to fertilize the young 

 seeds (ovules) in the ovary or seed-vessel below. 

 In the case of Cypripediums, however, the 

 case is a little different to the above general 

 rule, there being two pollen-bearing regions, one ' 

 on each side of the column behind the shield- 

 shaped staminode in front; and the stigmatic 



surface is the rounded back of the organ, below 

 the column concealed from view by the heel of 

 the slipper in these flowers. The pollen-masses 

 are treacle-like, and stick readily to the stig- 

 matic surface. 



Isolation and Self-fertilization to fix 

 Varieties. 



We have seen that to effect change and im- 

 provement in cultivated plants, we employ cross- 

 fertilization or hybridism, in addition to culture 

 and selection, as the motor forces in order to 

 obtain variations from existing and more or less 

 unsatisfactory types. But having actually se- 

 cured varieties of merit, we must face the diffi- 

 culty of keeping them pure, either as individuals, 

 or as races or strains. Individual varieties can 

 frequently be increased or propagated by cut- 

 tings, or scions, or by other well-known vegeta- 

 tive means — such as offsets, stolons, runners, 

 tubers, or layers. There are other cases, how- 

 ever, in which it is more convenient, or advisable, 

 to perpetuate our choicest strains or races of 

 plants by means of seeds. This is the case, for 

 example, with Cyclamen, Cineraria, Gloxinia, 

 Calceolaria, Primroses, Stocks, Antirrhinums, 

 Wallflowers, Begonias, and other so-called 

 "florists' flowers ". Of these it is now possible 

 to save seed that will very accurately "come 

 true " in colour, shape, size, habit of growth, and 

 other acquired characters. 



How then, let us ask, have their satisfactory 

 characters become so accurately fixed that they 

 can be relied on to " come true " from seeds 1 



We have seen that the hybrid offspring of two 

 species, or two different varieties, tends to be 

 variable as raised from seed ; but supposing that 

 amongst the seedlings there is one that ap- 

 proaches our ideal, what shall we do in order to 

 "fix" or render it stable 1 ? The answer lies in 

 the one word — isolation. We must take every 

 care that no foreign pollen obtains access to our 

 plant, and if necessary, — and it is nearly always 

 expedient or advisable, — we must carefully self- 

 fertilize its flowers with its own pollen. It is in 

 this way, by careful isolation and close in-and- 

 in breeding ( = self-fertilization), that all the 

 self-coloured strains of " florists' flowers " have 

 been raised. With such crops as Cabbages or 

 Turnips, and with Cucumbers and Melons, or 

 Tomatoes, the greatest care has to be taken to 

 keep the seeds of any particular varieties pure 

 by rigidly isolating them from the effects of 

 wind-borne or insect -carried pollen, and the 

 careful selection, or the rigid weeding out of 

 the bad forms known as " rogues ". 



