20 Plant Tissue Culture 



A decade later, as we have seen, the real prob- 

 lem was clearly formulated for the first time by 

 Haberlandt (1902,98) (Fig. 5). Where Rechinger 

 had sought to determine the limits of divisibility 

 of plant materials, Haberlandt boldly took his 

 point of departure directly from the cell theory 

 and assumed that down to the cell level there were 

 no limits of divisibility. He, therefore, chose to 

 work with single cells, an aim which we now look 

 upon as an elusive and as yet unattained ideal. 

 Further, Haberlandt fully appreciated the impor- 

 tance of the photosynthetic process to all living 

 material and consequently conceived the idea that, 

 since most plants contain green cells, by cultivat- 

 ing these particular cells the necessity for pro- 

 viding carbohydrate in the nutrient would be 

 eliminated and the problem of technique simpli- 

 fied. In this he apparently lost sight of the fact 

 that green cells are, for the most part, relatively 

 mature and highly differentiated cells which have, 

 to a great extent, lost their meristematic functions. 

 This ''simplification" led him to work with pali- 

 sade cells of Lamium, pith cells from the petioles 

 of Eichhomia crassipes, glandular hairs of Pul- 

 monaria, stamen hairs of Tradescantia, stinging 

 hairs of Urtica, stomatal guard cells of Ornitho- 

 galum, and many other similar materials. The 

 results were, without exception, disappointing 



