CYTOPLASMIC INCLUSIONS OF THE GERM-CELLS. 413 
pyronin and methyl green, BreinTs process or the carmine 
stains. Alizarin and crystal violet, and iron hasmatoxylin 
were used especially for mitochondria. 
Among fixatives I also used Regaud’s formol bichromate, 
but with little success in the bulk. With smears I found 
that this fixative gave an extremely useful result. Testes 
were smeared on a slide, fixed first in osmic vapour and 
then soaked for a short time in Regaucl. Afterwards they 
were transferred to 90 per cent, alcohol where they remained 
several hours. They were then stained in iron hgematoxylin 
by the long method. As a rule in such preparations the 
mitochondria alone were stained, astral rays of the spindle 
and chromosomes remaining colourless, but sometimes the 
nucleus in the growth stage took up the stain. As will be 
seen later this useful reaction helped me to clear up some 
doubtful points. Instead of further fixation in Regaud, 
smears were often transferred from the osmic vapour bath 
to water and alcohol and then stained. These also gave 
useful results. Bismark brown smears were not of much 
help. Under separate headings I have mentioned a few 
other special methods used by me. 
Of the species of Lepidoptera used, Smerinthus 
populi, Pier is brassicae, and Orgyia antiqua were 
most thoroughly studied in the order named. I carefully 
examined many preparations of Porthesia similis, Pieris 
rapae, Pygaera bucephala, Spilosoma lubricipeda 
(Arctia), Euchelia jacobseae, Cossus ligniperda, 
Bombyx 1 a nest r is and rubi, and Abraxas grossu- 
lariata. In Euchelia, Cossus, and Bombyx no maturation 
divisions were found, because my material was not sufficiently 
advanced in development. In Spilosoma only the degenerate 
u apyrene sperms ” were to be found because I took my 
larvas too late. Smears of Vanessa, Orgyia, and Porthesia 
were also examined. 
In later stages of this work Bensley’s permanganate of 
potash, acid fuschin stain was used, but no one stain was found 
to approach iron haematoxylin for certainty and usefulness. 
VOL. 62, PART 3. NEW SERIES. 29 
