Seedling Anatomy of Certain Sympetalae. 745 
be obtained. As a matter of fact, this sequence is found to occur in 
Convolvulus tricolor , which, therefore, serves to connect Type 2 with the 
Anemarrhena type. 
Summary. 
1. The present paper deals with the seedling anatomy of the following 
Natural Orders of the Tubiflorae : Convolvulaceae, Polemoniaceae, Hydro- 
phyllaceae, Boraginaceae, Labiatae, Solanaceae, Scrophulariaceae, Bignonia- 
ceae, and Acanthaceae. 
2. Much variation occurs in the size of the seedlings belonging to 
different species. Broadly speaking, in the smaller seedlings the transition 
region is short, and the rearrangements are concluded in the upper part 
of the hypocotyl ; while in the larger seedlings the region of transition 
is very extended (cf. Compton (4)). 
3. Cotyledons invariably two in number, and while the members 
of each pair are often unequal in size, this apparently has no effect on 
the essential transition phenomena. 
4. Cotyledonary tubes are present in members of all the orders 
examined, but their presence appears to have no bearing on the type of 
transition. Nearly related species having the same type of seedling 
structure show marked differences with regard to the cotyledonary tube. 
5. The prevailing type of transition, which is present in all the 
smaller seedlings, is Van Tieghem’s Type 3, and occurs in Polemoniaceae, 
Hydrophyllaceae, Boraginaceae, Labiatae, Solanaceae, Scrophulariaceae, 
some Bignoniaceae, and Acanthaceae. The larger seedlings possess a 
tetrarch root. In Convolvulus tricolor , var. major , the transition is a modi- 
fication of Van Tieghem’s Type 2, while the Anemarrhena type exhibited 
by Incarvillea Delayvei is approached through Convolvulus tricolor . 
6. Internal phloem is present in all Solanaceae and Convolvulaceae 
examined with the exception of Convolvidus tricolor , var. major, Nicotiana 
alata , Pehinia violacea , and Nierembergia gracilis (one seedling). Indica- 
tions are not wanting that the absence of internal phloem in these species 
is owing to the incomplete development of the tissues in the specimens 
examined. 
Bibliography. 
1 . Arber, A. : The Cactaceae and the Study of Seedlings. New Phytologist, 1910, p. 333. 
2. Chauveaud, G. : L’appareil conducteur des plantes vasculaires et les phases principales de son 
evolution. Ann. Sci. Nat. (Bot.), 9 e s^r., t. xiii, 1911, p. 113. 
3 . Clos, D. : Du collet dans les plantes. Ann. Sci. Nat. (Bot.), 3 e ser., t. xiii, 1849, p. 5. 
4 . Compton, R. H. : Seedling Structure in theLegumincsae. (Read at general meeting of Linnean 
Society, Feb. 15, 1912.) 
5 . Dangeard, P. A. : Recherches sur la mode d’union de la tige et de la racine chex les Dicotyle- 
dones. Le Botaniste, 1889, p. 75, 
