1915] Wing Hairs of Platyphylax Designatus Lov 
noticed by Mayer (6). This is due to the secretary activity of 
these cells and shows that hair formation has already started 
(Fig. 7). At this stage it was difficult to find places where the 
young hairs could be followed for any distance because, during 
the wing’s development, the hairs lie close against the surface 
and are shown in section as little circular or oval masses near 
the surface of the wing. 
With the further growth of the trichogen its nucleus, also 
enlarging, begins to flatten out against the vein adjacent to 
which it lies; it becomes elongated and occupies a position with 
its longitudinal axis parallel to the surface of the wing. With 
the growth of the nucleus its nucleole, which has for some time 
been a single large one, changes and by some process, fragmen- 
tation or otherwise, becomes divided into numerous smaller 
pieces which are scattered irregularly around within the nucleus 
(Fig. 7). The flattening of the trichogen nucleus becomes 
especially noticeable after the decrease in thickness of the wing 
and it is always found to be pressed against an outer surface of 
the vein adjacent to which it hes. With this narrowing of the 
wing the nucleus not only becomes more flattened but may be 
bent and curved and, in studying sections, trichogens are found 
which contain apparently two nuclei but these are in reality 
sections through two parts of the same one. It might be well 
in this connection to mention that the vacuole, Mayer (6) or 
vacuoles, Schaffer (7), present in the trichogens of the Lepidop- 
tera were not seen in Platyphylax. 
After emergence of the imago sections show that the parts 
already enumerated are still present except the large trichogens 
which, as such, could not be found. The hypodermis is still 
present on both surfaces of the wing but the nuclei have become 
irregular in outline and many of them flattened against the 
cuticula. The functions of the trichogens ended they have 
undoubtedly decreased very much in size and lost their identity 
amongst the general hypodermal cells. (Fig. 8). This last 
figure does not show the final condition as the hypodermal 
layers become more reduced and in places almost entirely rep- 
resented by the small irregular nuclei. 
Large surface hairs. The special enlarged cells from which 
later develop the large surface hairs do not become differentiated 
until the trichogens of the vein and marginal hairs are plainly 
