284 . 



plants are concerned, it is evident that they present a repetition of 

 parts horaotypal in structure and form, and thus illustrate one general 

 doctrine, that throughout the vegetable kingdom the parts are similar 

 to one another, and in nice accordance with the whole. 



" Such facts as the above incline us to the belief that the fibrous 

 veins of the leaf bear a morphological analogy to the stems of the 

 tree. We are inclined to regard the root, the stem, and the leaf as 

 the three distinct members of the fully-developed plant, these three 

 parts, however, being morphologically allied ; so that, to adopt the 

 phraseology of Professor Owen, as applied to another subject, they 

 may be called Homotypes. The plant thus becomes a unity, with 

 innumerable interesting diversities. 



" The same general truth may be arrived at by a reverse process. 

 Looking at the lowest plants in the scale, we at once perceive that 

 they are made up of parts which are a repetition of each other. And 

 we may remark that not only is one part of the same structure as 

 every other, but that when the parts are joined together they are 

 made to assume a set of forms, every one of which is the same as 

 every other, and as the whole. We see, for instance, that every 

 internode of the horsetail is the same as every other, and that the 

 topmost node is a type of the whole plant. We see that in the fern 

 every leaflet is of the same shape as its branch, and that every branch 

 is of the same shape as the whole plant. This, be it observed, is true, 

 not only of the structure of each part, but of the form which the com- 

 pound structure assumes. 



" Rising upward, let us now look at our common herbaceous plants. 

 Some of them, such as the hollyhock, the crowfoot, the lady's mantle, 

 send out a number of stems from near the root; and these plants send 

 out about the same number of main veins or midribs from the base of 

 the leaf I examined a great many Alchemillas, and found the same 

 number of stems from the root as of main ribs from the base of the 

 leaf; the crowfoot sends out five stems or so from its root, and it has 

 five main ribs in its leaf. Again, it may be observed how every 

 branch, with its leaves, is of the same form as its leaf, and how the 

 branch, with its leafage and the leaf, resemble the whole plant. The 

 common wood anemone sends out three stems ; at the top of each of 

 these stems is a compound leaf, divided into three smaller leaves, and 

 each of these smaller leaves has three main veins. Other plants, such 

 as the common thistles and the rag-weed, send up one main stem from 

 the root, and have one main vein in the leaf Observe, too, how 

 in such plants every leaf, with its ragged leaf, is a type of the whole 



