512 Osborn . — Some Observations on the Tuber of Phylloglossum . 
cortical cells. The youngest stages show the development of transverse 
walls in certain cells from which a cell mass subsequently forms, which 
swells externally and produces a 4 protophyll ’. The following account 1 of 
development of leaf bulbils is given. 4 An adventitious bud on a leaf shows 
first as a small, roundish, green cushion of meristematic tissue which has 
originated probably from one or more epidermal cells. This cushion 
develops into a roundish or egg-shaped cell mass which gradually elongates, 
and on which at an early stage rhizoids arise. The attachment of the young 
bud . . . shows that the main tissue of the leaf is undisturbed.’ These buds 
produce one to three 4 protophylls ’ and are firmly attached to the sub- 
stratum by rhizoids. Both 4 protophyll ’ and swelling are packed with 
starch grains, especially the latter, which develops a storage tissue. The 
parent leaf is 4 greenish at its upper portion but yellowish below and is 
always obviously broken off at its lower extremity The bulbil is subse- 
sequently freed by rotting away of the leaf. These bulbils Holloway 
compares with the protocorm of L. cernuum . 
If the term 4 protocorm ’ is to have any morphological value it is well 
that it should be limited to certain structures such as the extra-prothallial 
swelling of the embryo of L. cernuum and to the similar structures formed 
in L. laterale 2 and L. ramulosmn ? In the last two species the protocorm 
is of unusual size, but Holloway points out that in this’ large structure two 
portions may be recognized, 4 the original protocormous tuber surmounted 
by its two protophylls ’ and 4 the rhizomatous extension — an added feature 
to be interpreted apart from the original tuber ’. From an examination of 
material of L. laterale , collected by him in Tasmania, the writer is inclined 
to agree with this distinction. It is thus 4 the protocormous tuber ’ of 
L. laterale which is the homologue of the protocorm of L. cernuum . 
However, seeing 4 that vegetatively produced plants (from bulbils, gemmae' 
&c.) tend in their development to pass through stages in elaboration similar 
to young plants developing from spore or zygote ’, 4 Holloways extension 
of the term protocorm to the starch-containing bulbils of L. ramidosum and 
L. laterale seems perfectly justifiable. But it is unlikely that the protocorm, 
even so defined, has any phylogenetic significance . 6 It seems preferable to 
regard it as 4 an opportunist local swelling . . ., which, though biologically 
important ... is not really primitive.’ 6 
The biological importance of the protocorm becomes increasingly 
obvious as our knowledge of the ecology of those species of Lycopodium 
which produce it is enlarged. From Holloway we learn that the three New 
1 Holloway, J. E. (1916): loc. cit., p. 88. 
2 Holloway, J. E. (1914) : Trans. N.Z. Inst., xlvii, p. 73, and ibid. (1915), p. 277. 
3 Holloway, J. E. (1915) : loc. cit., p. 285. 
4 Lang, W. H. : Brit. Ass. Report, 1915, p. 706. 
6 Bower, F. O. (1908) : p. 225. 
6 Bower, F. O. (1914) : p. 565. 
