ios) Galas 
VOL. XXIV FEBRUARY, 1917 No. | 
THE GROWTH OF INSECT BLOOD CELLS IN VITRO! 
By R. W. Guaser. 
In order to obtain an insight into various pathological changes 
taking place in diseased insect tissue, I undertook a series of ex- 
periments dealing with the cultivation of such tissue in vitro. The 
degenerative changes occurring in normal and in pathological 
blood cells were especially studied for the reason that the blood 
is frequently used in diagnosing the health of a particular insect. 
In the polyhedral diseases of insects a general picture of the progress 
during the later stages of the disease can be obtained by examina- 
tion of the blood. This type of disease is recognized by the fact 
that nucleoprotein reaction bodies, termed polyhedra, are formed 
within the nuclei of the blood and certain other tissue cells. It 
was also of considerable interest to ascertain whether slides with 
growing insect tissue could be infected with the polyhedral disease 
virus and whether polyhedra would form within the nuclei of cells 
thus infected. By way of comparison, it was also of interest to see 
through what changes normal cells pass when permitted to degen- 
erate naturally. 
Incidentally, a number of observations were made in regard to 
the morphology and behavior of growing insect blood cells and I 
will present the observations in the hope of stimulating work 
along these lines. Although the cultivation of insect tissue is not 
new, this method of studying various embryological, morpholog- 
ical, and physiological questions pertaining to entomology has 
been almost entirely neglected and I am convinced that the culti- 
vation of tissues will greatly simplify the solution to many diffi- 
ult problems. 
Goldschmidt in 1915, by means of the tissue culture method, 
1 Contribution from the Entomological Laboratory of the Bussey Institution in codperation 
with the U. S. Bureau of Entomology. (Bussey Institution No. 125.) 
