I^O TRANS. ST. LOUIS ACAD. SCIENCE. 



PI. I. liar. 3J- A germinating seed in November. 



fig. 34. A seedling of the following spring, exhibiting the 8 cotyledons, the pri- 

 mary leaves, and upwards already some pairs of secondary leaves. 



The plates were drawn on stone, from nature, by Mr. Pau'us Roetter, late of St. Louis, 

 who had made himself so favorably known, more than twenty years ago, by the beautiful 

 Cactus plates published in the Report of the Mexican Boundary Commission, and who has 

 since greatly added to his fame and his usefulness by his artistic work in the Zoological 

 Institute in Cambridge. 



The Acorns and their Germination. 

 By Dr. George Engelmann. 



The structure of the acorns and the germination of the oaks 

 seemed to be so well known, that I did not pay much further 

 attention to it until my interest was excited by the information 

 that the germinating live-oak developed little tubers, well known 

 to the negro children and greedily eaten by them. The notes and 

 the specimens obtained from my South Carolina correspondents, 

 Messrs. H. W. Ravenel, W. St. J. Mazyck (who was the first to 

 notice this), and Dr. J. H. Mellichamp, enabled me to examine 

 the<yerminating live-oak and to compare it with other oaks in this 

 condition. I now studied the acorns, as many mature ones as I 

 could find in my collection, and the oak seedlings which I had, 

 as well as other seedling trees, carefully collected whenever I 

 could obtain them. The following are the results. 



In the tip of each acorn we distinguish, imbedded between the 

 two large fleshy cotyledons, first, the little caulicle, and then at 

 its upper end (towards the centre of the acorn) the two stalks or 

 petioles of these cotyledons ; between these the plumule is visi- 

 ble, more or less developed, usually only a truncate or slightly 

 notched or emarginate knob. These parts together are in the 

 difterent species and In difterent sized acorns usually from one 

 to three lines long and one-half to one line in diameter ; in very 

 small acorns sometimes smaller. 



The proportion of the caulicle to the stalks appears to be 

 constant in the same species, as I have satisfied myself by exam- 

 ination of numerous acorns of the same species from widely sepa- 

 rated localities. 



