Physiological Studies in Plant Anatomy 259 
were made in this green stem on March nth, and subsequent examin¬ 
ation on April 6th and April 18th showed suberisation of the exposed 
cells without any phellogen appearing. On the other hand deep cuts 
or pinpricks penetrating the endodermis were followed in the same 
time, not only by superficial suberisation but by phellogen production 
and activity beneath the injured endodermis. 
There are certain problems left in the literature which we think 
can be cleared up in the light of the above facts. 
Holden (12) has studied wound reaction in the Filicinean petiole, 
practically confining his attention to Leptosporangiate ferns. These 
ferns develop at an early stage Kroemer’s(i 5 ) “Secondary” type of 
endodermis with complete suberisation of at least one tangential as 
well as the radial wall (Basecke ( 3 )). It is therefore significant that 
whilst in all cases closure of the wound by processes of the nature 
of suberisation or wound gum formation was observed, meristem 
formation was only observed in wounds made at a region where the 
endodermis would only be partially differentiated or in Kroemer’s 
primary stage. To avoid recurrence to the case of the Filicineae, it 
may be pointed out here that natural meristems, analogous to 
periderm formation, are only reported from the Eusporangiate 
Marattiaceae (Massart(i6), loc. cit. p. 27) in which the endodermis in 
the petiole is missing and in the stem is only in the “primary” 
stage. 
Wachter( 29 ) has drawn attention to the fact that cuts on the 
cortical surfaces of the stem of Hippuris vulgaris L. are followed by 
suberisation and secretion of wound gum at the exposed surface, 
but that traces of meristem are never seen. As the stem of Hippuris, 
like that of most submerged aquatic plants, has a well-marked endo¬ 
dermis, this case is exactly parallel to the wound reaction described 
above for Camellia. This incapacity to form periderm seems general 
amongst aquatic Phanerogams (see Massart, loc. cit. p. 47). The one 
exception known to us, Polygonum amphibium L., is the one sub¬ 
merged aquatic stem in which a superficial cork layer is naturally 
present and in which cork is formed to heal cortical injuries: it is 
also the one submerged stem in which no trace of either a primary 
or secondary endodermis has been found. 
Massart also draws attention (loc. cit. p. 50) to the incapacity of 
the cortical cells of roots to form wound cork. He discusses it in 
relation to the age of the tissues, but the real difference between 
the behaviour of the young cortical cells of the root of Vida Faba L. 
and the shoot of Sambucus nigra L., contrasted by him, probably lies 
