60 BOTANICAL GAZETTE [JANUARY 
thing, but to a less marked extent. C. macrocarpa was less favor- 
able, but in one slightly wounded branch a few ray tracheids were 
observed. In C. Benthami they are very rare, but the material 
examined consisted only of a seedling with no wounds. Similarly a 
seedling of C. tortulosa failed to show any, and in C. occidentalis they 
seem to be entirely absent. 
The southern hemisphere genus Callitris, with its sub-genus 
Tetraclinus, has been described by BAKER (13) as entirely without 
ray tracheids. JEFFREY, however, observed them in Callitris in 
connection with the leaf trace, and I have seen them quite widely 
distributed, but always in small numbers. Throughout the 
genus they are invariably marginal, never standing alone. Fig. 9 
represents a characteristic ray tracheid in C.. arborea. Two lots 
of material of this species were examined, and the mature wood 
of both contained ray tracheids of this type. There seemed to 
be no relation to injury, for they were equally abundant inside and 
outside a wound callus. Small branches, however, in neither lot 
showed ray tracheids. Fig. ro demonstrates the type of tracheid 
characteristic of C. calcarata. Here they are longer and lower 
than in the above mentioned species, and, as there, the bordered 
pits are confined to the horizontal wall next the parenchyma cells. 
This material was entirely unwounded as far as could be seen. 
C. columellaris showed the same type of ray tracheids, even in nof- 
mal tissue. C. robusta showed the largest number of tracheids of 
any species examined. They were present quite frequently in the 
mature wood, whether injured or not, but seem to be quite absent 
in the seedling stem. The ray tracheids are characteristically long 
and low, like those of C. arborea. C. cupressoides, as far as could 
be seen, lacks ray tracheids entirely, even in root wood. Fig. 1 
shows a marginal tracheid in Tetraclinus articulata. They are 
present fairly abundantly in the mature wood, but are in general 
lacking in branches and twigs. One branch in which they were 
normally missing contained a few in the wound cap over a slight 
injury. 
Mayr (14) has described ray tracheids in Thuja plicata, and I 
have found them quite common in both that species and in 
BR PRS est Mrs. AO verre 
eS PM RE ne Seay ee eee STE 
AT ae eae 
Aare Ke Bit grils, 
