4 NATURE STUDY 



number of plants of both the large and the small flowered 

 species. For several seasons these flourished and even 

 increased in number. After a while the flowers of pubes- 

 cens began to grow smaller, until in size some of them 

 barely surpassed those oi parviRoi'uni . We noted that the 

 latter underwent no change and speculated as to the cause 

 of the change in the former, attributing it to deterioration 

 consequent upon removal to an unnatural habitat. Now 

 that the same variation has been observed to take place 

 among plants growing in their native homes, that hypothe- 

 sis must be abandoned and the variation must be consid- 

 ered as occurring in the regular course of nature. 



There is nothing in the shape of the flower called the 

 pink lady-slipper to suggest the name. The showy part 

 of the flower is a pouch with a closed but easily opened 

 fissure down the whole length in front. In the yellow spe- 

 cies the corresponding part is reall}' shaped like a slipper, 

 or rather a baby's sock. In France the flowers are called 

 " les sabots de la Vierge." The large opening in the top 

 has its "raison d'etre," as we shall see when we come to 

 consider the parts of the flower and their uses. A similar 

 construction of the slipper is found in C. spectabile, while 

 in C. arietimim the extremity or toe is .so pointed as to have 

 suggested the common name, ram's head. 



The flowers in the orchid family have undergone such 

 extreme modification that it is b}^ no means easy to make 

 out the different parts and compare them with the corres- 

 ponding parts of an ordinary flower. Yet there is a single 

 type underlying the whole, and the family is doubtless de- 

 rived from ancestors who possessed regular flowers. With 

 all the enormous difference between the large and small, 

 the showy and the plain, the tropical and the non- tropical,, 

 the flowers throughout the family are formed on the same 

 plan. There are always three sepals, even where, as in 



