1893. ] The Roots of Ranunculacee. II 
phanerogams and it only needed Russow’s!® article to prove 
that this type was not a universal one. Mainly through the 
study of embryos he compared the roots of phanerogams with 
those of vascular cryptogams. He found that the rootsof all 
phanerogams did not follow the Helianthus type, for in the 
embryos of several Leguminose and in many older roots of 
dicotyledons one could not trace the epidermis under the root- 
cap, on the contrary the dermatogen entered the primary 
meristem of a continuous layer; and he found that in many 
roots there was no distinction between the dermatogen and 
the periblem, or between the dermatogen and calyptogen, 
and sometimes the periblem and plerome were not distinctly 
separated. 
In 1874 appeared Janczewski’s!® very important memoir. 
He reviewed the work that had preceded his, especially crit- 
icising Reinke, asserting that he endeavored to prove a pre- 
conceived conclusion, and that his investigations were not 
sufficiently accurate and extended to base important deduc- 
tions upon. In making his investigations Janczewski studied 
the roots of embryos, developing roots, and mature roots, the 
best results being obtained from the study of the latter, and 
he bases his conclusions upon this study. He proposed five 
principal types of meristem structure at the growing-point in 
the roots of phanerogams. His five types are as follows: 
First type, roots having four independent primary tissues 
at the vegetative point, and so four initial groups, a calyp- 
trogen, a dermatogen, a periblem and a plerome. He placed 
but two plants in this type, Hydrocharts and Pistia. + 
Second type, roots having three independent primary tis- 
sues, a sharply defined calyptrogen and plerome, and between 
these an initial group from which arise the cortex and epi- 
dermis, or perhaps no true epidermis present, the outer layers 
of the cortex taking its place. This is the type to which he 
assigns most of the monocotyledons. 
Third type, roots with three primary tissues, the plerome 
and periblem being sharply defined but the epidermis and 
root-cap having a common origin. Here he would include 
most dicotyledons. 
15 Vergleichende Untersuchungen, etc., der Phanerogamen, ausgehend von 
der  Grsirsse der Marsiliaceen. Mém. Acad. de St. Petersburg, VII. xix 
(187 
a Spitzenwachsthum der Phanerogamenwurzeln. Bot. Zeit. 1874. 
Rec oe sur le developpement des radicelles dans les Phaa. Ann. des 
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