CHAP. I. 
LATICIFEROUS TISSUE. 
35 
are determined by BischofF to be mere accidental forms, caused 
by their irregular compression, when growing in knots or 
parts that are subject to an interrupted kind of developement. 
They may be found figured in Mirbel’s Elemens, tab. x. 
fig. 15.; and in Kieser, fig. 56. and 57.; but the best view 
of their origin and true nature is in Slack’s plate, fig. 33., 
in the Transactions of the Society of Arts, before referred to. 
Link defines them to be short spiral vessels with attenuated 
extremities, and regards them, in his latest works, as young 
spiral vessels, or as the commencement of spiral vessels, which, 
instead of lengthening, grow together by their ends. 
Vascular tissue always consists of tubes that are unbranched. 
They have been represented by Mirbel as ramifying in some 
cases : but this opinion has undoubtedly arisen from imperfect 
observation. When forming a series of vessels, the ends of 
the tubes overlay each other, as represented in Plate II. 
fig. 15. 
Slack states that the membrane is often obliterated at 
the place where two vessels touch each other, and that trans- 
verse bars only remain under the form of a grating : this 
appearance is produced by the remains of the spiral fibre, se- 
veral of whose convolutions are partially uncovered by the 
absorption of the enveloping membrane. It would hence ap- 
pear that ducts open into each other at their points of contact. 
Sect. V. Of Laticiferous Tissue^ or Cinencliyma, 
The earlier anatomists were acquainted with the existence 
of milk vessels in many plants, but they gave no account of 
them sufficiently exact to distinguish them from other kinds 
of tissue, and, accordingly, they have been usually looked upon 
as forms of Pleurenchyma, or of Trachenchyma, or as inter- 
cellular cavities. 
It was reserved for Prof. Schultz of Berlin to show’ the 
general existence of such vessels, and their real nature. The 
memoir upon this subject, in which his most recent views are 
stated, has not yet been published ; but there is an abstract 
of it by M. Auguste de St. Hilaire in the Annales des Sciences, 
D 2 
