1883.] Mr Potter, On the Ml aocotytetiyMtiJ* plant. 395 



believe that the red colour of very young leaves and of dying leaves 

 in the autumn is also dependent on the presence of tannic acid. 

 Doubtless also the phlobaphenes or colouring matters of the bark, 

 e.g. the red amorphous colouring matter occurring in the periderm 

 of the oak, are formed from tannic acid, since many tannic acids, 

 such as Quercitannic and Cinchona tannic acid, — when boiled with 

 dilute acids — yield red amorphous bodies resembling the phlo- 

 baphenes in every respect. 



(2) On the junction of the Root and Stem in the Monocoty- 

 ledonous plant. By M. C. Potter, B. A., St. Peter's College. With 

 Plate XI. 



In the root of both Monocotyledons and Dicotyledons we 

 find the fibrovascular bundles arranged on the radial type, the 

 transition from the radial type of the root to the collateral type 

 of the stem has been investigated for Dicotyledons by Miss Gold- 

 smith 1 , who found that in the tigellum the Xylem and Phloem of 

 each collateral bundle separated from each other, the Phloem 

 bundles uniting in pairs, the Xylem bundles after rotation uniting 

 in the centre, so that the protoxylem which is in the stem the 

 most internal part of each Xylem bundle becomes the most 

 external part in the root. As far as I am aware no one has traced 

 the course of the fibrovascular bundles from the regular radial 

 type in the root to the irregularly scattered collateral bundles in 

 the stem of the Monocotyledon. 



Professor Sachs 2 in his text-book of botany thus describes the 

 germination in Monocotyledons. 



" Germination begins either at once by the lengthening of the 

 roots (their protrusion causing in Grasses the rupture of the root 

 sheath which envelopes them) or, as is more commonly the case, 

 the lower part of the Cotyledon lengthens and pushes the end of 

 the root together with the plumule which is enveloped by the sheath 

 of the Cotyledon out of the seed, while its upper part remains 

 in the endosperm as an organ of absorption until the endosperm 

 is consumed. In Grasses however the whole of the plumule 

 projects from the seed, the scutellum only remaining behind in it, 

 in order to convey to the embryo the reserve material of the seed." 



There are then in the Monocotyledon two modes of germina- 

 tion ; as examples of these I have taken Zea Mais as a type of the 

 germination in the Gramineae, and Phoenix Dactylifera to represent 

 the more common mode of germination. 



1 Beitrnge zur Entwicklungsgeschielite der Fibrovasalnwssen im Stengel und in 

 der Hauptwurzel der Dicotyledonen, Inaugural-Dissertation, Zurich, 1876. 



2 Text-book of Botany, 2nd English Edition, p. 619. Bot. Zeit. 1862 and 1863. 



VOL. IV. PT. VI. 28 



