154 BOTANICAL GAZETTE [AUGUST 
hydrated form of cellulose, and is found in L. saccharina and L. digitata in various 
states of hydration. It appears to be produced in the young sieve plates by the 
action of a ferment on the already formed cell wall, but is afterward accumulated 
by deposition from the protoplasm, both on the surface of the sieve plate and on 
the lateral walls of the tube. (4) The histology of the sieve tubes agrees with 
that of spermatophytes. The only contrast between the method of obliteration 
of the sieve tubes in Laminariaceae and Pinus is that in the latter the heads of the 
slime strings are still visible on the free edge of the callus cushions, and the path 
of the slime strings can be traced throughout the callus mass; while in Macro- 
cystis and Laminaria the callus is laid down by the protoplasm of the sieve tubes 
over the heads of the slime strings, so that they are buried by the overlying callus 
and no perforations can be traced through the rod. (5) The protoplasmic 
connecting threads throughout the tissue of M. pyrifera and L. saccharina wete 
demonstrated, but it is impossible to be certain of their formation in case ° 
secondary attachment.—S. Y AMANOUCHI. 
Primitive angiosperms.—Miss SARGENT has developed more fully her view 
as to the origin of the monocotyledons,'5 which was stated formally in 1993: 
The present paper of course deals with the characters of primitive angiosperms, 
but this is a necessary corollary to the recently developed phylogenetic position of 
monocotyledons. It is an abstract of a course of eight lectures delivered for the 
London University about a year ago, and even then leaves the discussion of te 
origin of the flower to the recent paper by ARBERand PARKIN.*® Itis impossible 
to discuss the numerous lines of evidence presented and the inferences drawn 
from them. In general it may be said that facts are treated with a free hand and 
not always critically, that they are often related to one another with great bold- 
ness, and that the conclusions are in some cases more evident than the proofs. 
Reasons for believing in the monophyletic origin of angiosperms are 
presented, and with the recent development of our knowledge of vascular anatomy, 
it is questionable whether there exists today any serious objection to this view 
And yet, perhaps it is well to have the situation summarized for us. 
he reconstruction of the primitive race of angiosperms is based chiefly ied 
floral structure, stem anatomy, and number of cotyledons. The outcome is @ 
plant with a strobiloid flower (as Magnolia), with a cambium, and with 1° 
cotyledons. A comparative study of pteridophytes, gymnosperms, and ne 
sperms would seem to make the last two conclusions inevitable, and the 
least partially true. 
e real contention of the author, however, is the origin of 
donous condition. There is a very full discussion of all possible 
the monocotyle- 
alternative 
15 SARGENT, ErHer, The reconst 
Annals of Botany 22:121~-186. figs. 21. 
16 ArBeR, E. A. N., and Park, J., On the origin of angiosperms. _ 
Soc. Bot. 38:29-80. 1907. See Bot. GAZETTE 443389. 1997- 
ruction of a race of primitive angios} 
I a * 
Linn. 
