^. Collecting and Subdividing Plant Materials 



The preservation ot structural details of cells and tissues is in- 

 fluenced by the condition of the plant at the time of collecting 

 and by the subsequent preparation for killing (fixation) . For the 

 study of normal structure, select healthy, representative plants. Re- 

 move the plant or the desired part with the least possible injury to 

 the sample. If the material is to be killed at once, follow the pro- 

 cedure outlined in Chap. 3. If the material cannot be killed prompdy, 

 it should be stored and transported in such manner that bruising, 

 desiccation, molding, and other injuries are minimized. Do not use 

 material that has been obviously damaged in storage or shipment. 

 The unsatisfactory slides obtained from such material are likely to 

 be interpreted by uncritical observers as the result of poor technicjue. 

 Dried herbarium specimens can be softened and sectioned to make 

 slides in which it is possible to determine the gross features of 

 vascular arrangement or carpellary organization (Hyland, 1941). 

 However, such material is not suitable for detailed microscopic study. 



1 he following general directions are introduced at this point for 

 the use of readers who have selected subjects on which to work. The 

 reader who seeks suggestions concerning suitable and tested subjects 

 should turn to Part II and use the recommendations made therein 

 in conjunction with the present chapter. 



LEAVES 



Remove a leaf or leaflet by cutting the petiole, without squeezing 

 or pulling the petiole. The vascular bundles in the petioles of some 

 plants become dislodged easily. For transportation or brief storage, 

 place the leaves between sheets of wet toweling paper and keep in 

 a closed container such as a tin can or a Mason jar. If the leaves 

 appear to be wilted on arrival in the laboratory, freshen them in a 

 moist chamber before processing. 



[5] 



