1886.] BOTANICAL GAZETTE. 11 
tersuchungen,’ published in 1884. The only original paper upon 
the subject published in this country is that of Barnes on Cam- 
panula Americana.* 
All these authors agree in their testimony as to the difficulty 
of performing this work, and so the demonstration of these recon- 
dite, but very important, facts has been left entirely to trained 
investigators. Knowing that the pollen-spores of monocotyle- 
ons were much more favorable for study than those of dicotyle- 
dons, which are certainly too difficult for ordinary observers, and 
desiring to discover some plant in which these almost inaccessi- 
ble facts could be seen with comparative ease, the pollen-spores 
of Tradescantia were selected. ‘The result was so signally suc- 
cessful, and the methods were so repeatedly tested, that we pre- 
sent them in this paper. 
flowers that had been open for some time, such seeming to re- 
spond more readily. A power of 250 diameters was constantly 
used in the work, though the figures of the plate are drawn larger 
(460 diameters) for the purpose of securing clearness of detail. 
e spores are elliptical in optical section, and the extine is so 
thin and so free from the customary markings of pollen-spores 
that the details of the interior can be easily seen, In a few min- 
? For review see Bot. Gazette, x. 328. 
® Bot. Gazette, x. 349. 
*Practical Botany, p. 16 
* Physiological Botany, p. 430. 
