3i8 PROCEEDINGS OF THE 



from the simple ones, the first change noted is that in some specie?^ 

 tliere is a slight depression across the top, by which the apices 

 of the combined leaves on each side of the orifice slightly overtop 

 the latter. In another species the depression is more pronounced : 

 in another it becomes a distinct notch ; in another the notch is 

 deeper and tlie plant is two-lobed. These are all indications of 

 the progressive separation of the two leaves of which each plant 

 is composed. In different species the separation becomes more 

 and more apparent, until we find forms in which the two leaves 

 are separated nearly or quite, to their base. This progression 

 will only result in the plant having but two perfectly developed 

 leaves, besides the withered remains of the old ones, at the same 

 time. Other species, however, will show a tendency to develop 

 a new pair of leaves before the old pair have begun to shriveL 

 and from such forms the transition is easy to such as normally 

 have two pairs always present, and from these to others having 

 three or four pairs present on each growth, forming a tuft. The 

 passage of this type to that with several or many leaves in a 

 rosette is exhibited by many species. Such a progressive change, 

 although finally leading to several different types of modification, 

 is produced without any gieat development of the stem. But the 

 development of the shrubby forms from these can also be traced. 

 Several of the primitive species with age gradually develop short 

 stems and branches, which, becoming covered with earth, are 

 more or less subterranean. Some, however, gradually develop 

 short stems above the ground. From such types a passage to 

 another and distinctly shrubby form is arrived at by the internodes 

 developing in varying degree according to the species. Finally, 

 you may have a shrub 15 ft. high, formed by the superposition 

 of one segment on another, each having a short woody stem 

 (internode) at the base. I am not mentioning their specific 

 names, because most of tlie plants shown arc new species, and 

 liavc not yet been named. It is not possible to show all the 

 stages of connection, as that would require a gi'eater number 

 of specimens than could be brought together, but examination 

 will, without showing every link in the chain, make sufficiently 

 clear the manner in which the lines of development have pro- 

 gressed, by a slight modification here, and another there, until 

 a totally different type has become evolved." 



Reference to a large numl^er of living plants and blossoms. 



