tATICTFEROUS VESSELS OP HEVEA. 571 



1. Laticiferous tubes absent -.—Caletiece, Amperece (?) , Phyl- 

 lanthea, JBrideliece, and Bicinocarpece, ex p. 



2. Laticiferous tubes replaced by articulated sacs ; individual 

 cells of approximately equal length : — Bicinocarpece e>x^.,Acaly- 

 phece, and Dalechampiece. 



3. The individual cells of the articulated sacs are of different 

 length, either owing to the partial resorption of transverse walls, 

 or to the elongation of individual cells, the latter at present 

 appearing more probable, as phenomena indicating resorption 

 could not be observed : — Aleurites, Garcia, and Joliannesia. 



4. Inarticulated (ramified) thick-walled laticiferous tubes, with 

 peculiar apical growth, &e. : — Hippomanece, Euphorbiece, and 

 Crotonece. 



It will be noticed that Dr. Pax has in no case observed articu- 

 lated tubes in the sense of true vessels, such as I hare found to 

 occur in Manihot and Hevea. Only a partial absorption of the 

 transverse walls is admitted as possible, but not probable, in the 

 case of Aleurites, &c. 



In the author's classification of the Order by anatomical cha- 

 racters (which corresponds with the morphological classification 

 of Miiller), the occurrence and character of the laticiferous 

 tissue play an important part. I give the outlines of his arrange- 

 ment, so far as it affects genera which have been referred to in 

 my papers. 



I. Phyllanthoideae. (Laticiferous tubes absent.) 



II. Crotonoidese. (Laticiferous tubes or articulated sacs 

 present.) 



A. Acalyphineae. (Laticiferous tubes articulated.) The 



Hevece are doubtfully included in the fourth group of 

 this division. 



B. Hippomanoineae. (Laticiferous tubes inarticulated.) 



This division includes, besides the Crotonece and Euphor- 

 biece, the Hippomanece, under which head, among other 

 genera, Hippomane, Sura, Jatropha, and Manihot are 

 enumerated. 

 This classification differs from that of Bentham as regards both 

 the genera which have formed the special subject of my papers. 

 First, Hevea, which is placed by Bentham in the subtribe Jatro- 

 phece of his tribe Crotonece, is transferred by Dr. Pax (in agree- 

 ment with Miiller), though with an indication of doubt, to a 

 group of the Acalyphinea. The latter, as stated above, are 

 mainly characterized in the anatomical classification of Dr. Pax 



LINtf. JOUEN.— BOTANY, TOL. XXI. 2 T 



