May 31, 1912] 
When these remarkable activities were first 
observed it seemed incredible that we were 
witnessing a normal mode of erythrocyte for- 
mation. The experiments were consequently 
repeated many times, subjected to various 
tests, and the results analyzed in the light of 
all the criticism that could be brought to bear 
upon the subject. Temperature, media, evap- 
oration, staining reaction and degenerative 
changes have been carefully considered. It is 
a pleasure to state that Professor R. J. Terry 
and Mr. C. H. Danforth, of the anatomical 
department, have also carefully followed these 
erythroblast activities and haye kindly sub- 
jected the results to valuable criticism. In 
brief, after careful study the conclusion seems 
unavoidable that we are here confronted with 
a normal mode of formation of mammalian 
erythrocytes by a process of budding and con- 
striction from the parent erythroblast. It is 
interesting that this result is in accord with 
the discarded theory of Malassez (1882), on 
the origin of erythrocytes from bone marrow 
cells by budding, while at the same time the 
investigations were made and the conclusions 
drawn entirely independent of any previous 
knowledge of his work. 
In addition to the formation of typical 
erythrocytes, another type of activity con- 
sists in the production of either very small 
buds or slender, elongated, rod-like processes 
which may ultimately segment into a vary- 
ing number of subdivisions about one third 
or one fourth the size of the average ery- 
throcyte. These correspond very closely in 
size and form to blood platelets. As for 
the amount of cytoplasm remaining with the 
nucleus, after the constriction off of an ery- 
throcyte, it may vary from a small rim about 
the nucleus to a quantity occasionally even 
larger than the erythrocyte to which the 
parent cell has given rise. No conclusive 
evidence of a migration of the nucleus from 
the cell has as yet been obtained. However, 
in the case of the smaller erythroblasts the 
constriction may take place so close to the 
nucleus that it may present the appearance of 
nuclear extrusion, and it is readily conceivable 
SCIENCE 
875 
that in some cases the constriction may be 
such as to leave behind a practically cyto- 
plasmic-free nucleus and thus account for the 
free erythrocytic nuclei occasionally found in 
the blood. That the fundamental process 
here described is one of cytoplasmic con- 
striction rather than of nuclear extrusion is 
still further demonstrated by the fact that 
occasionally a single large erythroblast was 
observed to give rise to even two buds, both 
of which became detached from the parent 
cell. 
Granting that we are justified in the above 
conclusion, various questions naturally present 
themselves; among others the behavior of the 
erythroblasts in different media; the factors 
involved ia the formation of hemoglobin and 
its separation from the erythroblast; the sub- 
sequent assumption by the liberated globule 
of a dise or cup-shaped form; the fate of the 
nucleated remainder of the erythroblast, and 
the possible relationship between lymphocytes 
and erythroblasts. Investigation bearing on 
these problems is under way. The present 
preliminary statement will be followed as soon 
as possible with a full description of tech- 
nique, detailed data, and figures upon which 
these conclusions are based. 
V. E. Een 
DEPARTMENT OF ANATOMY, 
WASHINGTON UNIVERSITY MEDICAL SCHOOL, 
April 25, 1912 
ON THE APPEARANCE OF ALBINO MUTANTS IN 
LITTERS OF THE COMMON NORWAY RAT, 
MUS NORVEGICUS 
AFTER several failures to breed the Norway 
rats in cages, we have finally succeeded in 
raising them in captivity by means of an 
improvement in the cages and diet, as well as 
in general treatment. 
This successful experiment was begun more 
than two years ago and we are just getting 
the litters which belong to the third generation 
born in captivity. It may be added that in 
all cases the brothers and sisters of the same 
litters were mated as I wished to determine 
the combined effects of close inbreeding and 
captivity. 
