252 



THE ORCHID WORLD. 



[October, 1916. 



MINUTE STRUCTURE. * 



IN an article published in the Gardeners 

 Chronicle of May 9th, 1885, Dr. 

 Masters called attention to the relation 

 that subsists between the minute structure of 

 the vegetative organs of plants, especially of 

 the leaves, and their functions, as indicated by 

 Stahl and others, and gave some illustrations 

 selected from some well-known Orchids in 

 cultivation. These illustrations, which are 

 transverse sections of the leaves magnified 

 forty diameters, bear strong evidence of the 

 minute structure being indicative of the con- 

 ditions under which the plant grows. Admit- 

 ting the partial and incomplete nature of the 

 examination, it was sufficient to enable the 

 observer to state the general conditions as to 

 light and shade and supply of water the 

 plants required, and these conclusions were 

 found on consultation with practical culti- 

 vators to be near approximations of the truth 

 in all cases. It is thence evident that could a 

 sufficiently comprehensive knowledge of the 

 minute structure of the vegetative organs of 

 Orchids be brought within the reach of Orchid 

 growers generally, its influence for good in 

 the cultural treatment of the plants would be 

 of an enduring kind. Dr. Masters remarks 

 that : — 



" In the leaves of Orchids we have the com- 

 ponent structures apparently arranged with 

 reference to the conditions under which the 

 plant grows naturally. Some grow in full 

 sunshine, and are constructed accordingly. 

 .Some thrive in diffused light. Some bear a 

 long period of drought uninjured ; others 

 could not endure the privation of water even 

 for a few hours. Some are so constructed as 

 to adapt themselves to varied conditions with 

 little trouble, and these, of course, are the 

 plants the gardener finds it easy to cultivate. 

 In others the adjustment is so delicate that 

 they cannot suffer any change without incon- 

 venience ; these are the plants the gardener 

 has a difficulty in keeping alive, and which 

 even in their native countries are dying out, 

 elbowed out by their more robust and less 



* Extracted from Veitch's "Manual of Orchidaceous Plants." 

 Part 10. 



exacting brethren on the principle of the sur- 

 vival of the fittest." • 



If, then, the conditions noted in the fore- 

 going quotation are made manifest in the 

 leaves of Orchids by their minute structure, 

 and we have every reason to believe that this 

 structure is a part of the result of their 

 " environment " and that it enables them to 

 perform their important functions to the best 

 advantage of the plant, it must be worth 

 while to ascertain what that structure is, in 

 order to obtain reliable data for cultural treat- 

 ment. Confessedly imperfect as were the 

 investigations of Dr. Masters up to the date 

 of publication, their import and their intrinsic 

 value to cultivators when they shall have been 

 more elaborately worked out is, however, so 

 evident that we have been induced to continue 

 the examination with the view of adding 

 something more to our knowledge of the sub- 

 ject, and with the hope of inducing others 

 who may have leisure at their disposal to take 

 it up more comprehensively. 



The sections of leaves, stems and roots that 

 are here illustrated were made by Mr. N. E. 

 Brown, of the Kew Herbarium, and all bear 

 ample testimony to the accuracy and care 

 with which they have been executed. The 

 technical description and terminology of the 

 various tissues of plants must be sought for in 

 text books devoted to the subject ; we can 

 only here offer so much explanation as will 

 render the illustrations intelligible to the 

 general reader. 



All complete vegetable structures consist 

 of cells for the most part indistinguishable by 

 the naked eye. Each living cell in what is 

 conveniently regarded as its normal state at 

 the epoch of commencement of growth con- 

 sists of (i) a transparent colourless membrane 

 called the cell-wall which encloses (2) the 

 protoplasm, " the physical basis of life " as it 

 has been aptly termed by Professor Huxley, 

 which forms a layer closely lining the cell- 

 wall, (3) a denser rounded mass of the proto- 

 plasm called the nucleus, which is either 

 embedded in the layer of protoplasm lining 

 the cell-wall, or is suspended in the middle 

 of the cell by fine threads of protoplasm, the 

 intervening space (4), the vacuole, being filled 



