46 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
too long, produce very abnormal effects, causing not only extraordinary 
shrinkage, but also lateral pressure between the cells resulting in angular 
outlines. Imperfect development of the asters of the spermatocytes 
is also evidence of imperfect methods, unless the achromatic figures 
differ markedly in different orders of insects, which is hardly probable. 
As my figures show, the asters involve practically the entire cytoplasm, 
an effect which, of course, could not be attributed to reagents. 
The achromatic figures can be studied with the greatest ease in the 
living dividing cell. I have studied them thus for hours at a time on a 
hot stage. But I have found it impracticable to study the whole proc¬ 
ess of mitosis in this way, because of the evident rapidity with which 
some phases are passed through and the unusual slowness of other 
phases. This is especially true of the telophase of mitosis, particu¬ 
larly of the last maturation division. 
«/ 
Material. 
For purposes of comparison, I have studied Grapta silenus Edwards, 
a smaller butterfly, also native to the North Pacific coast region, and 
which, in the adult form, strikingly mimics in color the bark of trees 
on which it feeds. Being a hibernating form, its life history differs as 
much as possible from that of Papilio rutulus, and I find that while, 
in the main, the spermatogenesis agrees, yet there are minor differences 
which have aided me considerably in understanding some difficult 
matters in Papilio. When not otherwise specifically stated, Papilio 
rutulus is the form referred to in this work. 
Papilio rutulus is one of the largest, most beautiful, and most striking 
insects on the Pacific coast of North America. Being especiallv 
abundant here at Ellensburg, Washington, it has proved a very favor¬ 
able subject for study. 
I have seen no evidence of dimorphism, yet it resembles very much 
the tiger swallowtail, Papilio turnus, of southeastern United States. 
The female of Papilio rutulus measures nearly five inches extended, 
the male about four inches. It is deep yellow with conspicuous black 
markings on body and margins of wings, the internal posterior parts 
of the hind wings being also shaded with a patch of brown and two 
shades of blue. Underneath the hind wings there are also two brown 
spots and a line of blue spots extending parallel with the posterior 
