314 POPULAR SCIENCE MONTHLY. 



different methods of distribution of seeds and fruits; another, of 

 parasitic plants; and still another showing the various devices by 

 means of which plants catch animals. 



As an example of the graphic and thorough way in which these 

 illustrations are worked out, the pines may be cited. There are fos- 

 sils; fine specimens of pistillate and staminate flowers in alcohol; 

 cones; a drawing of the pollen; large models of the flowers; models 

 of the seeds, showing the embryo and the various stages of germina- 

 tion; cross and longitudinal sections of the wood; drawings showing 

 its microscopic structure; pictures of adult trees; and samples illus- 

 trating their economic importance. For the last, the long-leaved 

 pine of the South is used, and samples are exhibited of the tur- 

 pentine, crude and refined; tar and the oil of tar; resin; the leaves; 

 the same boiled in potash; the same hatcheled into wool; yarn, bag- 

 ging and rope made from the wool; and its timber split, sawn, and 

 dressed. 



The series illustrating the fertilization of flowers begins with a 

 large drawing, adapted by one of the students from Gibson, showing 

 the gradual evolution of the belief in cross-fertilization from 1682, 

 when ISTehemiah Grew first declared that seed would not set unless 

 pollen reached the stigma, down to Darwin, who first demonstrated 

 the advantages of cross-fertilization and showed many of the de- 

 vices of plants by which this is accomplished. The special devices 

 are then illustrated with models and large drawings. First comes the 

 dimorphic primrose; then follows trimorphic Ly thrum, to the beau- 

 tiful model of which is appended a copy of the letter in which Dar- 

 win wrote to Gray of his discovery: 



" But I am almost stark, staring mad over Lythrum. ... I 

 should rather like seed of Mitchella. But, oh, Lythrum! 



" Your utterly mad friend, 



"C. Darwin." 



Models of the cucumber, showing the process of its formation, 

 and the unisexual flowers complete this series. Supplementing this 

 are models and drawings of a large number of flowers, illustrating 

 special devices by which cross-fertilization is secured, such as the 

 larkspur, butter and eggs, orchids, iris, salvia, several composites, the 

 milkweed, and, most interesting of all, the Dutchman's pipe. This 

 is a flower that entices flies into its curved trumpet and keeps them 

 there until they become covered with the ripe pollen. Then the 

 hairs wither, the tube changes its position, the fly is permitted to 

 leave, carrying the pollen thus acquired to another flower with the 

 same result. 



