314 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the abaxial curve depends on the length of the leaf and the size of the- 

 pinnae. In Cycads the abaxial portion of the leaf-trace is directly 

 connected with the length of the leaf ; and in most genera the pinna- 

 trace is supplied from the adaxial margin of the leaf-trace nearest 

 to the pinna. In some of the Palmacefe the forms of leaf-trace 

 and pinna-ti-ace are directly related to the type of vascular system found 

 in the stem, and appear to be independent of the size of leaf and the 

 manner of its development. In Dicotyledons two distinct types of leaf- 

 trace, with their varieties, have been found. The type of leaf-trace 

 with strands forming a ]-ing is found in woody plants, excepting: 

 those with basipetally-developed leaves ; the type open on the adaxial 

 face is found in herbaceous and Avoody plants with basipetally- 

 developed leaves ; in herbaceous plants with acropetally-developed 

 leaves the " open " type of leaf -trace is provided with an intrame- 

 dullary reinforcing system. The factors which control the form of 

 leaf-trace and its system of branching are :— (1) Systematic position ; 

 (2) the length of the leaf and the size of its appendages ; (3) the order 

 of development of the pinna? ; (4) the type of vascular system found in 

 the stem. Among Ferns (1) and (2) are operative ; (1), (2) and (3) 

 among Cycads ; (4) among Monocotyledons ; and (3) and (4) amon^ 

 Dicotyledons. 



Lycopodium prothallia from New Zealand.* — C. J. Chamberlain 

 publishes an account of the prothallia and sporelings of three New 

 Zealand species of Lycopodium, prefaced by a historical resume of papers- 

 previously published on Lycopodium prothallia. The present paper 

 treats of material supplied by A. P. W. Thomas of Auckland — Lycopo- 

 dium lateraJe, L. volubile, and L. scariosiim. Summarizing his results^ 

 the author says : — 1. Lycopodium lateraJe has a green, leafy prothallium • 

 and there is a protocorm-protophyll stage in the embryogeny. L. mluhile 

 and L. scariosum have subterranean prothallia with no protocorra stage,. 

 but the early leaves have the structure of protophylls. 2. In L. scariosum 

 and L. voluUle the sporeling has a radial stele. The adult plants have 

 a banded stele. 3. The outer part of the ray of the radial structure 

 consists almost exclusively of pitted tracheids with scarcely any spiral 

 vessels, but becomes lignified long in advance of the large tracheids of 

 the metaxylem, and should be regarded as the protoxylem. 



Lycopodium prothallia in America.f — E. A. Spessard announces his 

 discovery of prothallia of Lycopodium in America after a prolonged and 

 careful search in Michigan, and describes the conditions under which the 

 specimens (twenty-one prothallia and over fifty sporelings) were found. 

 The prothallia of L. obscurum and L. lucidulum were previously unknown; 

 the other species found were L. comjdanaium, L. clavatum and L. anno- 

 tinum. In order to prove that he is describing genuine prothallia, he 

 gives figures of the structure, showing antheridia, archegonia, and the 

 fungus-infected region. 



* Bot. Gaz., Ixiii. (1917) pp. 51-65 (2 pis.), 

 t Bot. Gaz., Ixiii. (1917) pp. 66-76 (figs.). 



