XXVIIT 
ARTIFICIAL PARTHENOGENESIS IN THE EGGS OF 
FROGS 
During the first years of his work and later the writer 
vainly applied the chemical methods of artificial parthenogenesis 
to the eggs of fishes and of frogs. The reason for this failure 
may possibly lie in the relative impermeability of the walls of 
these eggs for the chemicals used. The walls of the eggs of 
Fundulus are, as long as they are normal, not only impermeable 
for salts but also for water. It seemed desirable that a method 
of artificial parthenogenesis for vertebrates should be found 
since it is so much easier to raise the larvae of vertebrates than 
of invertebrates. It is under the circumstances no surprise that 
such a method was found almost accidentally. In 1907 Guyer 
published a paper in which he reported that by injecting lymph 
or blood into the unfertilized eggs of frogs he succeeded in 
starting development and even in obtaining two tadpoles. 
Considering the importance of these experiments and _ since 
they seem to have been overlooked, the writer feels justified 
in quoting part of Guyer’s note: 
During three successive springs (1905-7) the writer has experi- 
mented on unfertilized frog eggs by injecting them with blood or 
lymph of either male or female frogs. In all some fifteen hundred 
eggs have been so operated upon. Shortly before the time for laying, 
the eggs were taken from the uterus with every precaution to prevent 
contamination by sperm. Those nearest the cloacal opening were 
always set aside as a control and in not a single instance did any of them 
develop. The other eggs were pricked with a very fine-pointed capil- 
lary tube which had previously been charged with lymph and cor- 
puscles by dipping it into the lymph or the blood of another frog. 
In eggs so treated numerous instances of cell proliferation and 
embryonic development have been observed, provided the eggs were 
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