1893.] THE MICKOSCOPE. 55 



style. I have made excellent slides at 10 A. M., or later in the 

 day, unless it was so hot and dry as to dry up the stigmas. I 

 get the best slides of pollen tubes just as the bloom turns purple 

 — often by hundreds on the same stigma. 



vSome notes I made July 2, 1891, read thus : " The stigma was 

 beautiful. The adherent pollen grains had developed tubes in 

 great numbers, some just beginning to sprout, while others had 

 already sent their tubes down the style to the ovule. The pol- 

 lens lodged on the branches of the stigma, with their tubes, are 

 easily seen with a " C" eyepiece and a -^-inch objective. The 

 tubes are slightly yellow tinged, and are in plain contrast with the 

 pure white arborescent stigma. The pollen grain does not often 

 sprout at the point of its contact with the stigma, but the tubes 

 come out at certain points prepared by nature for that purpose — 

 an opening in the extine through which the tube of the intine 

 like a glove finger pushes out. As the tube pushes out I see the 

 extine rolling out in a collar-like ringf. The tube at first is like a 

 nipple, but as it grows into a tube it hugs closely around the cir- 

 cumference of the pollen grain, and thus it feels for the stigma. 

 Very often when it has appeared too far away it makes a square- 

 angled turn after encompassing ^ of the circumference of the pol- 

 len grain, and thus arrives at the stigmatic tissue, where it passes 

 down over the surface of a stigmatic cell, not penetrating into it, 

 until it comes to an interspace between the cells. Here it finds 

 an entering point by absorbing the contents of the gland cells 

 of the stigma through their walls without breaking the cells open. 

 Thus it gains space to enter into the stvle by the application and 

 use of the material of the cell, in its way, for its own nourishment. 

 Sometimes the tube makes almost a complete ring around the 

 pollen grain before it reaches the stigma, and sometimes it makes 

 two right-angles in its course before it reaches the stigma. Each 

 grain seems to send out only one tube. These transparent stigmas 

 are very fine to behold when covered with the pollen grains and 

 tubes by hundreds. 



It needs a little careful manipulation to mount the stigmas, but 

 the inexperienced will soon learn to take out the little ovule 

 stigmas with a needle or small knife-blade. Use a well-arranged 

 lens fixed so that both hands are free. Place it in a drop of water 

 on the slide. After the stigma is thoroughly wet, apply the cover 

 with a film of water spread over it with a small knife-blade. The 

 most important thing is to get the air away from the stigma, and 

 it may become necessary to add a very little alcohol to the water. 

 Alcohol spoils delicate tissues by shrinking them, so applv a very 

 little on a knife-blade dipped in the alcohol bottle. Mount in a 

 drop of equal parts of alcohol, glycerin, and w r ater if you choose. 

 Having selected good specimens to preserve, place a drop of 

 glycerin, or of liquid glycerin jelly, or of any mounting medium, 



