130 



The Germination of Pollen.* 



Cultivating pollen grains in the ordinary way laid down in 

 the books, although satisfactory in results, has proved too laborious 

 when it is desired to provide tubes in considerable quantities, as 

 for example, for use by classes in laboratory practice. As a 

 primary variation from the inverted drop upon the cover glass, 

 the sugar solution was placed upon glass slides and pollen dusted 

 into it. The slides were placed upon a small block of wood m a 

 dinner-plate and over all a bell jar lined with filter paper dip- 

 ping into the water upon the bottom of the plate. Under such 

 treatment the tubes push out with surprising vigor. When it is 

 desired to study the germination, a portion of the syrup may be 

 removed to another slide, a cover-glass applied and the prepara- 

 tion is ready for the high power. However, the progress of ger- 

 mination can be watched upon the original slide by placing it 

 under a low power and without a cover-glass. This method 

 proved so successful that watch-glasses were next employed, and 

 these were more convenient for holding the sugar solution and 

 did not prevent the general study with low objectives. However, 

 with abundance of material it is easier to dip out a portion, apply 

 the cover- glass and look immediately with the higher powers. 



As a next step, artists' porcelain well-slabs were obtained. 

 Some of these slabs contained eight wells of the size of watch- 

 glasses, one slab fitting over and becoming a cover for the one 

 below. Slabs with smaller wells, twenty-one in number, and 

 provided with special covers, have proved the most convenient 

 The record of the pollen placed in each particular well can be 

 conveniently kept upon a paper marked with numbers to corres- 

 pond with the wells. Labels pasted upon the spaces between the 

 wells have not proved satisfactory. The wells may be left open 

 to the sunlight by placing a glass bell jar over them. The rapidity 

 with which moulds develop in the syrup will su^-o-est the impor- 

 tance of taking all precautions to exclude germs from the cultures. 



A supply of sugar solution is easily kept of full strength in a 

 bottle having a bulb-stopple, with which it can be dropped into 

 the well and diluted to the desired strength as required. 



With these slabs, pollen of many sorts can be similarly tested 



* Read at the A. A. A. S. meeting at Cleveland in 1888. 



