102 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 
With this object in view, the following experiments were 
performed. Membrane formation was produced by treating 
eggs of S. purpuratus with butyric acid. The eggs were then 
divided into two dishes containing the same hypertonic solution 
(50 c.c. of sea-water+8 c.c. 24 m NaCl). One of these dishes 
was maintained at a certain temperature, the other at a tem- 
perature 10° higher. At different intervals, portions of the eggs 
were replaced in normal sea-water of room temperature, and the 
minimum exposure necessary to allow a certain percentage of the 
eggs to develop was noted. The results for the eggs of five 
different sea-urchins (S. purpuratus) are contained in Table 
IX. One noteworthy result was that at temperatures above 
20° C. the eggs were harmed by the hypertonic solution. Of 
course, this does not hold for the eggs of all sea-urchins, as my 
experiments at Woods Hole were usually performed at a tem- 
perature of over 20°C. It is probably connected with the fact 
that the temperature of the water at Pacific Grove never is as 
high as that at Woods Hole in summer. 
TABLE IX 
Temperature vor Productherot |Temperature Coefficient 
Numerous Larvae | Q« for 10°C. 
sie Nas Gaal Glen pete ato toe 210 minutes | mee 
Exp. 1. SAC Ree eae 40 minutes | Qro=5 
RPEES Are CIT eee eee, Nl 160 minutes et 
Exp: 2. PUDAICs a yantah ore _ about 55 minutes Qu =3 
Tin ey Sh Oe Crel te Wapao nes atee about 112 minutes | ( 927 
Exp.s. S202 | Coe aam eee: | about 32 minutes Qu =3-5 
= Be Oe aE ee a oh | about 50 minutes | 5 
Exp. 4. ARNG er tens Ceca all eggs die ' 
Hees NON Ges eames | about 35 minutes | ° 
SEs OGL OR ee eT all eggs die 
temperature coefficient in settling this question. I myself applied this criterion to 
the sphere of the physiology of development, and caused my pupils, C. D. Snyder 
and 8S. S. Maxwell, to employ it in settling the question whether the heart beat 
and the transmission of nervous impulses depend upon chemical or physical pro- 
cesses. The temperature coefficient found in the heart beat was of the order of 
magnitude for chemical processes. 
