Maron 22, 1912] 
growth of this membrane are moderate in amount, 
the lecithin content of the membrane is of medium 
value (9 per cent.). At phase (2) the lecithin 
content is high (15-23 per cent.). During phase 
(3) the lecithin content again assumes a medium 
value (8.5 per cent.). The fat content is much 
lowest at phase (2) (= traces). In phases (1) 
and (3) this figure is 6 per cent. and 7 per cent., 
respectively. It has been shown that these values 
are not produced by variable amounts of contam- 
inating yolk. The results seem to lend some sup- 
port to Overton’s theory of the lipoid nature of the 
cell membrane; and indeed to indicate that that 
theory may be extended so as to apply to a mem- 
brane of cells. At any rate, here is one case where 
changes in degree of permeability of a cellular 
membrane to substances rich in fat (yolk) are pre- 
ceded or accompanied by a change in the lecithin 
content of the component cells of the membrane. 
Some Chemical and Hybridization Experiments in 
Invertebrates: Max Morse, Trinity College. 
A number of crosses were attempted at the 
Harpswell Laboratory, South Harpswell, Maine, 
between the nemertean, Cerebratulus, and various 
invertebrates, such as Hchinarachnius, Ilyanassa, 
Strongylocentrotus and others, both by simple mix- 
ing of eggs and sperms and by the application of 
hypertonic solutions and other reagents known by 
previous experiments to cause polar bodies to form 
or even to induce the earlier morula divisions of 
the egg. Of the several crosses attempted, only 
one was in any degree successful, this being 
Cerebratulus egg by Ilyanassa sperm, the polar 
bodies being extruded and the earlier segmenta- 
tions passed through. However, even here it was 
found impossible to prolong the growth of the 
embryo to gastrulation, although temperature, 
salinity, alkalinity and other factors were consid- 
ered. The cross in question was checked against 
errors in manipulation, contamination, ete. No 
experiment made according to the methods of 
Godlewski, Kupelwieser, et al., where excessive 
amounts of sperm were used, were successful, nor 
were experiments involving normal fertilization, 
preceded by or followed by hypertonic or other 
parthenogenetic reagents, successful in causing 
even polar bodies to form. Hence Cerebratulus is 
similar to several other forms where attempted 
hybridization was found to be futile. 
A Comparison of the Retardation Produced by 
Rapid and Slow Electrons (Beta Radiations) of 
Radium in the Growth of Various Seedlings and 
a Consideration of the Relative Importance of 
SCIENCE 
463 
Chemical and Physical Factors in the Process: 
KE. D. Conepon, Cornell University Medical 
College. 
The method of comparing the effect of the rapid 
and the slow electrons consisted in the exposure of 
one lot of dry seeds (Synapis nigra, Panicum 
germanicum, Amaranthus monstrosus, Nicotiana 
tobacum and Papaver somniferum) to rapid elec- 
trons and another lot to a like intensity of rapid 
electrons plus secondary slow electrons coming 
from a lead tube. Both sets showed a retardation 
which decreased in amount with shortened ex- 
posure. The slow electrons had one fourth as 
great ionizing power in the air as the rapid elec- 
trons. Their retarding effect, however, was much 
greater than one fourth that of the rapid. In one 
case it was twice as great. Therefore, when very 
small seeds are taken so that the non-penetrating 
electrons can distribute their effect through the 
whole seed, the slow electrons, relative to their 
ionizing power in the air, are much more biolog- 
ically effective than the rapid. It was also found 
that absence of seed coat increased greatly the 
effect, not only of the slow (non-penetrating) but 
of the rapid (penetrating) electrons. The placing 
of the embryo side of the seed toward the radium 
had a like effect. Those seeds with the greatest 
diameter were least retarded, and vice versa. Thus 
even in such small organisms, the largest having a 
diameter of only 0.67 mm., factors governing ab- 
sorption play a great role in determining their 
sensitiveness. To determine the importance of 
chemical make up, pairs of seeds of like diameters 
but very unlike constitution as to starch and fat 
were exposed. The testa had been removed and 
the embryos all turned toward the radium. The 
pairs of species having seeds of like diameters 
showed almost identical degrees of retardation. 
The differing sensitiveness of the species here 
used must then be referred to physical rather than 
chemical differences in the seeds. 
Studies in Developmental Energetics. I. The 
Changes in Chemical Energy during the Devel- 
opment of Fundulus heteroclhitus: Otto GLASER, 
University of Michigan. 
Studies on the Artificial Production of Grafted 
and Multiple Embryos: A. J. GOLDFARB, College 
of the City of New York. 
By a modification of the Herbst method of 
treating sea-urchin eggs, it was possible to produce 
either (1) fertilized eggs without their membranes, 
and with the blastomeres completely separated, (2) 
the same but with the blastomeres only partially 
