:202 ANNUAL REPORT 



food is digested. In Lathrcea and Bartsia it is only the proto- 

 plasma of the button like cells in the interior of the cavities, 

 which sends out mobile threads to hold the prey.. Of course 

 •other plants may be yet detected, that will upset all our artifi- 

 cial classifications, which do not occur in nature, but are simply 

 made to enable us to study more systematically. 



The first group of carnivorous plants which perform move- 

 ments for catching living food, is comjjosed of the species of Pin- 

 guicula, of which about forty are known, and which resemble 

 each other so closely, that no one except a botanist could at sight 

 distinguish between Pinguicula calyptrata from the mountains of 

 New Granada and the P. vulgaris growing in the Hartz moun- 

 tains. The localities in which these plants grow are also quite 

 similar. Both in the old and new world they grow in moist 

 places, upon the margins of creeks, upon moors and in swamps, 

 farther south they exchange the cool regions for higher alti- 

 tudes. Very rich in species are the high mountains of Mexico. 

 Each species in a southern region is quite local, whilst those 

 growing in the arctic and subarctic regions have a very wide dis- 

 tribution. The best known species is P. vulgaris, extending from 

 North America, north of Mackenzie, to Labrabor, Greenland, 

 Island to Siberia, and from the Baikal mountains through Europe 

 to the Balkan, Alps and Pyrenees. 



The delicate looking plant possesses violet-blue flowers, borne 

 by slender stems, starting from a star of leaves resting upon the 

 soil. The leaves are elongated-oval or tongue-shaped, and of a 

 yellowish-green color; their edges are turned up, transforming 

 each leaf into a broad channel or groove, with a flat bottom 

 [Fig. 9 (9-11)]. This groove is covered with a sticky, colorless 

 slime, secreted by numerous glands upon the upper surface of 

 the leaf. There are two kinds of glands; one looking like a 

 button upon a stem, can be seen with the naked eye, and re- 

 sembles a small mushroom [Fig. 9 (9)], and is composed of 

 eight to sixteen radiating cells supported by a single tubular one 

 as a stem. The second kind of gland is composed of eight cells, 

 grouped together in a wart-like body, j)i'OJecting but a little 

 above the surface of the leaf. One square centimetre of a leaf 

 contains about 25,000 slime-secreting glands, so that the whole 

 plant, usually composed of nine leaves, carries about half a mil- 

 lion of such glands. If these glands are simply touched for a 

 -short time, perhaps by drops of rain, no change is produced, but 

 ^ continuous pressure by any solid substance, for instance by in- 



