170 Dr. P. Hildebraad on the Impregnation in Orchids 



3-3^ millim.j and a length of 10-15 millim. ; its cavity is a very 

 narrow channel, on the walls of which are to be seen three 

 ridges, of an irregularly undulated appearance ; these ridges are 

 the placentse that are not yet fully developed ; there are no in- 

 cipient ovules upon them. The stigma of the expanded flower 

 is covered with numerous utriculi separated by a copious viscid 

 substance. If the pollen is applied to this viscid surface of the 

 stigma, very soon, at least after two days, the labellum of the 

 flower folds up round the column, and the petals and sepals in- 

 cline over it, and, withering in about nine days, do not fall off, 

 but are to be found at last on the top of the ripe fruit. If the 

 pollen is not applied to the stigma, the flower remains unchanged 

 for a long time ; in from twenty to thirty days it begins to wither, 

 and falls off: during this time the placentae have not grown in 

 any way. 



After the application of the pollen to the stigma, the petals 

 and sepals soon begin to wither, as stated above ; at the same 

 time the column begins to swell hemispherically, and the pollen- 

 tubes, forming a cord, pass through the channel of the column. 

 On reaching the cavity of the ovarium, they divide into three 

 parts, and each of these parts divides again into two, running 

 down on each side of the placentse. Soon after the application 

 of the pollen to the stigma, the ovarium began to enlarge both 

 in length and in diameter ; in eleven days, the placentse were 

 more deeply undulated, and in twenty days they were dis- 

 tinctly divided into two parts, each part being fringed irregu- 

 larly ; no ovules were yet to be seen. Now I thought that the 

 enlargement of the ovaria which had no ovules on their placentse 

 was only abnormal, and that no ovules ever would be formed. 

 Therefore I did not examine a fruit before the 3rd of March : 

 this fruit had originated from a flower impregnated on the 5th 

 of January. I found the placentse quite covered with ovules 

 showing very different degrees of development : there were some 

 incurved, the outer and inner coats enclosing the nucleus ; some 

 where the nucleus was still protruding ; and some that appeared 

 only as a papilla a little incurved, and surrounded at its base by 

 the incipient coats. The cords of the pollen-tubes were in an 

 unchanged state on both sides of the placentse. At this time 

 the fruit had a diameter of 20 millim., and a length of 60 milHm.; 

 it had become green and succulent, and there were some sto- 

 mata on its surface ; its much enlarged cavity was not yet filled 

 up with the ovules. Next a fruit that had originated on the 

 10th of January was examined on the 13th of April, and all the 

 ovules were found in a perfect state, filling up the entire cavity 

 of the ovarium ; the embryo-sac was to be seen distinctly, but 

 no pollen-tube had reached it. On the 32nd of April, the ger- 



