366 
REVIEWS. 
“ since there exist both Cryptogamic and Phanerogamic plants with 
“ and without vessels.” 
Dr. Caspary does not disguise the extreme difficulty of deter¬ 
mining in some cases whether we have to deal with single cells or 
with a row of confluent cells. In the first place, the cross partitions 
which separate the cells in the compound vessel are very frequently 
but partially absorbed. It is usual in many plants to find traces of 
these transverse septa in the form of a network or transverse bars, 
the primary membrane only which occupied the interstices having 
been absorbed. But even this absorption of the primary membrane 
may often take place at a late stage in the development of the vessel, 
if indeed it do not often persist until the vessel ceases to take any 
active part in the economy of the plant. The age of the tissue, 
therefore, is a second consideration not to be lost sight of. Since 
then the technical distinction between cells and vessels rests upon 
the absorption more or less of the intervening partitions, which 
absorption may be of the smallest possible amount, we believe that 
in very many cases it will ever remain a matter of doubt whether a 
plant be vascular or evascular from Dr. Caspary’s point of view. 
We therefore think it undesirable to adopt the terminology proposed 
by Dr. Caspary for the general purposes of plant anatomy, though 
in some special investigations it may be well to employ it. At the 
same time we w'ould not be understood as wishing to imply that the 
careful investigation into the composition of the various tissues of 
plants is unworthy of the endeavour of botanists competent to un¬ 
dertake such inquiries. Bar from it. We regard Dr. Caspary’s 
essay as of no small interest, and as a contribution to Vegetable 
Anatomy likely to help us to future important generalisations. The 
principal features we shall briefly note. 
The author’s attention appears to have been first directed to the 
subject by his researches on the Anatomy of the Nymphseaceae, in 
which he found the so-called vessels to be made up of series of dis¬ 
tinct cells. The absence of vessels in the wmod of Coniferae (exclu¬ 
sive of Gnetaceee) and Cycadeae has long been known. Decently 
Mettenius has pointed out that Ferns, Lycopods, Equiseta, &c. do 
not possess compound vessels, and this observation Caspary confirms 
and extends to Isoeteae. We observe, by the way, that Schacht, in 
his 4 Lehrbuch,’ refers to the composition of the vessels of Isoetes, 
and states the same fact as Caspary A Around this nucleus many 
additional observations have been accumulated, especially by our 
author, enabling him to announce some general propositions, which, 
however, require, as he most fully admits, to be securely established 
upon yet more extended comparative investigation. We have stated 
that he finds the greater number of Monocotyledons to be destitute 
* Vol. i. 227. Speaking of the vessels of the abbreviated axis of Isoetes , he 
says:—“Die Querwande dermit einem SpiralbandeversehenenZellenscheinen hier 
nicht durchbrocheii zu sein.” 
