LEADING PRINCIPLES OP SCIENCE. 11 



and from the regular-flowered crowfoot to tho distorted monks-hood by a series 

 graduated in like manner. 



16. N.-itura non saltus facit, said Linna?us, in evident allusion to this beau- 

 tiful principle, which will constitute one of tho most interesting themes of botanical 

 study. 



17. Accomodated Forms or organ3 is a phrase applied to another principle 

 m the Divine plan, the reverse of the first. This principle appears in tho adaptation 

 of different organs in different species to one common use ; of which there are many 

 iamiliar 



18. Examples. Thus, tho slender vine requires support. Now it throws out a 

 tendril for this very purpose, grasping whatever object it may reach, as in the grape. 

 Again, the prolonged leaf-stalk answers tho same end, as in Clematis. Again, tho" 

 supple stem itself, by its own coils supports itself, as in the hop ; anil, lastly, ad- 

 ventitious rootlets in the ivy. 



19. Another illustration. Reproduction i3 the general office of the seed; 

 but this end is also accomplished, in different species, by nearly every other organ, 

 by buds, bulblcts, bulbs, tubers, cuttings, scions, and even leaves. 



20. Another. This principle is also traced in tho nutritious deposits of plants, 

 which are generally made in tho fruit ; but often tho root serves as tho reservoir in- 

 stead, or even tho stem. And in case of the fruit, the rich deposit is now found in 

 tho pericarp of the peach, the calyx of tho apple, tho receptacle of the strawberry, 

 the cotyledons of tho almond, tho bracts, flower-stalks, &c, of the pine-app!e. Thua 

 God's boundless resources of skill can accomplish either one purpose in a thousand 

 different ways, or a thousand different purposes by a single organ. 



21. Arx'.ested Forms. This principle, demanding a wider range of generaliza- 

 tion than either of tho foregoing, we state rather as a hypothesis, that the student 

 may hereafter test its probability by his own observations. The flowering plants 

 which clothe the earth in such numbers, constituting tho apparent vegetable world, 

 are in truth but a minor part of it in respect to numbers. Numerous tribes, of lower 

 rank, embracing thousands of species, reach far down the scale, beyond the utmost 

 limits of tho microscope. Now a principle of analogy seems to pervade these ranks, 

 called the principle of arrested forms, binding all together in one consistent whole, 

 proving that for tho vast realm of vegetation there was but one plan and one origin. 



22. Tiie Hypothesis stated. The successive tribes of vegetation, beginning 

 with the lowest, have each their type or analogue in the successive stages of em- 

 bryonic growth in tho highest tribe. 



23. More explicitly : the flowering plant, in the course of its growth from 

 the pollen grain to the completed embryo, passes necessarily through a series of 

 transient form3. Now, suppose tho development of the plant arrested at each of 

 these stages, so that these transient form3 become permanent, we should have a 

 series of organisms analogous to the various tribes of Flowerless Plants ; the Pro- 

 tococcus, e. g., an arrested pollen grain ; the Oscillaria, an arrested pollen tube ; and 

 so on up to the Marsillea, whose organization answers to that of the full- formed 

 ombryo of tho flowering plant. Thus wo might truly say of tho lower plants that 

 they are the arrested forms of the higher. 



2-1. Individuality op the Plant. Tho plant is both material and immaterial. 

 It3 form and substance is tho material, its life tho immaterial. The material com- 

 mences existence as a single cell, and is ever changing. Tho immaterial gives to 

 that cell it3 individuality, and fixes inevitably its law of development, so that it 

 crust grow up to become such a plant as it is, and by no possibility any other. 



25. Illustration. Tho embryonic cell of arose may not differ materially, in tho 



