Macrozamia heteromera, Moore. 9 



a number of irregular crooked lines, meeting each other at acute 

 angles, and having the characters of periderm, but apparently 

 crossing and surrounding healthy tissue. Formations of the same 

 sort were seen in the secondary phloem and cortex. G. Gapelli- 

 niana shewed similar anomalous cork, but less well developed. 

 A figure is given of a transverse section of this species with a 

 line of periderm running approximately parallel to the stem 

 surface, partly in the cortex and partly in the phloem, and also a 

 high power drawing of part of the pith of Cycadeoidea Gocchiana, 

 Car., shewing a band of periderm. The latter was described by 

 Caruel under the name of Raumeria Gocchiana, but he did not 

 recognise the nature of this formation, only speaking of it as a 

 zone of tissue in the pith whose cells were arranged in rows. 

 Caruel's specimen was re-examined by Solms-Laubach, and the 

 cutting of fresh sections revealed the existence of a cylindrical 

 closed periderm. 



In describing Medullosa anglica Scott 1 points out that from 

 the first the periderm formation is very irregular, and that in one 

 of the specimens where it is little developed " it already appears 

 here and there in the form of loops or rings enclosing leaf-trace 

 bundles, or portions of sclerenchyma." 



As regards recent Cycads, Scott 2 speaks of the occurrence of 

 anomalous periderm as "an abnormal condition which is often met 

 with." But although from this it would appear to be familiar to 

 workers in this field, I have only been able to find it described in 

 one case, that of a Stangeria paradoxa stem investigated by 

 Solms-Laubach 3 . Here a closed sheath of periderm of an irre- 

 gular " sackform " occurred, which at one level extended so as to 

 coincide with the stem surface, and diminished in diameter as it 

 was traced up or down the stem. The trunk was rotten at the 

 base, and one of the two growing points was dead, and the author 

 suggests that the periderm formation was for the purpose of 

 arresting the invasion of decay into the sound part of the stem. 



Anomalous periderm formation is illustrated both in the stem 

 and roots of the specimen of Macrozamia heteromera which forms 

 the subject of these notes. If sections are cut of the remains of 

 the adventitious roots whose bases are still attached to the stem, 

 they are found, as would naturally be expected, to be the seat of 

 considerable cork formation. The tissues are in a bad state of 

 preservation, so that the structure is not altogether easy to make 

 out. A second periderm, apparently also pericyclic in origin, has 

 arisen inside the first in at least one of the roots, and has invaded 



1 Phil. Trans. Roy. Soc. Vol. 191, B, 1898, p. 97. 



2 Studies in Fossil Botany, 1900, p. 452. 



3 "Die Sprossfolge der Stangeria und die iibrigen Cycadeen," Bot. Zeit. 1890, 

 p. 214. 



