CONTRIBUTIONS TO BOTANY. 
207 
raphe just described, the ramifications of which appear to issue 
from the ehalaza, where the integuments are united in a solid 
disk. The souree whenee these vessels derive their origin in the 
ehalaza may, however, be traced to the main cord of the raphe, 
which forms a thick bundle running from the hilum to the basal 
disk. The two integuments are so closely agglutinated together, 
that it is not easy to determine through which of them the 
branching portions penetrate ; the main cord is manifestly in 
the outer tunic. 
On two former occasions, I recorded two very unusual cases 
in which the raphe becomes entirely peripherical, that is to 
say, first runs in the usual manner up one side from the 
hilum to the ehalaza, and then returns again along the oppo- 
site side of the seed to the hilum — in both directions in the form 
of a simple continuous cord : the one instance was in Stemv- 
nurus *, a genus of the Icacinacece ; the other appeared in Cucur- 
• bitacea-\. I have yet to show that a similar abnormal couise of 
the raphe is universal, as far as I have been able to ascertain, 
in Rhamnacea. The consideration of this peculiar development 
will be deferred till I have detailed all the curious circumstances 
connected with it, in a memoir just completed. 
In the Euphorbiacece, the raphe, as a thick simple cord, runs 
in a straight line from the hilum to the opposite chalazal extre- 
mity, where it is imbedded in the outer tunic, which is some- 
times as thick and fleshy as in Magnolia, and w'here, as in that 
genus, a distinct bony shell intervenes between that coating and 
the thin inner integument : this raphe perforates the shell 
through a small diapylar foramen, to reach a small ehalaza at 
the base of that integument; and out of this ehalaza T have 
sometimes observed other vessels distributed over the area of the 
tegmen, in ten or fewer radiating and almost parallel bands 
which extend from the base to the apex. The existence of an 
external aniline, in ivhich the main cord of the raphe is im- 
bedded, and which is often of a scarlet colour, is common to all 
the Euphorbiaceee •, and this is always more or less fleshy, and 
invariably invests the bony shell usually denominated the testa, 
but which shell, in all cases, I have found devoid of tracheal 
vessels. 
The development of the ovule in its early stages is subject to 
many modifleations, which, in different families of plants, are 
often constant; and these afford good characters, hitherto little 
noticed. Some interesting facts on this head were recorded by 
* Ann. Nat. Hist. 2 ser. x. 33 ; Contributions to Botany, i. p. 83, pi. 13 ; 
Trans. Linn. Soc. xxii. p. 98, pi. 19. figs. 6, /, 8, .9. 
