82 METHODS IN PLANT HISTOLOGY 



Studied in the hanging drop. For facilitating such cultures there are 

 many devices, such as hollow-ground slides, glass rings, rubber rings, 

 etc. (Fig. 17). A device which is better for most purposes, and which is 

 easily made by any student, is to cut a square or round hole f inch in 

 diameter in a piece of pasteboard | inch thick, 1 inch wide, and 1| 

 inches long. The pasteboard is then boiled to sterilize it and to make 

 it fit more closely to the slide. While the pasteboard is still wet, press 

 _ it to the slide, make the 



II II culture in a drop of 



^ ,, ^^ ^ . J , water or culture solu- 



riG. 17. — Ine hanging-drop culture 



tion on the cover, and 

 invert the cover over the hole. A little water added at the edge of the 

 pasteboard from time to time will keep it from warping and will at the 

 same time provide a constant moist chamber. 



In collecting material for mitotic figures in anthers it is necessary to 

 examine fresh anthers, if one wishes to avoid a tedious and uncertain 

 search after the anthers have been imbedded. By teasing out a few 

 cells from the apex and a few from the base of the anther the stage of 

 development is readily determined, and anthers which do not show the 

 desired stages can be rejected. By allowing a drop of eosin or methyl 

 green to run under the cover, the figures are more easily detected. The 

 actual progress of mitosis has been observed in the stamen hairs of 

 TradescanUa. If care be taken not to injure the hairs or let the tem- 

 perature drop, a mount in water, or in 1 per cent sugar solution, or in 

 the juice of the plant, may live long enough for a study of a complete 

 mitosis, which takes 2 or 3 hours. 



MICROCHEMICAL TESTS 



Botanical microchemistry has developed to such an extent that it 

 has become an independent subject, like bacteriology. We shall con- 

 sider only the commonest tests which are needed constantly by stu- 

 dents of morphology. For a thorough presentation of the chemistry of 

 the cell, we are still looking forward with great anticipation to a forth- 

 coming book by Dr. Sophia Eckerson, whose critical tests and analyses 

 we have observed for many years. In the meantime, Pflanzenmikro- 

 chemie, by Dr. 0. Tunmann (Gebriider Borntrager, Berlin), is recom- 

 mended to those who read German. Zimmerman's Botanical Micro- 

 technique (Henry Holt & Co., New York) is still recommended to those 

 who must rely upon English. We shall give only a few tests, but in 



