462 KING. [Vor. XIX. 
appearance and in the development of the cells of Bidder’s 
organ in the two sexes, Marshall states that the “degenera- 
tion of the male genital gland may be regarded as taking the 
form of a reversion to the more primitive ovarian type.” Ac- 
cording to the investigations of Spengel (35), Semon (30), 
Goglio-Tos (12), and Bouin (2), the anterior portion of the 
genital ridge, which develops into the fat body, is composed 
‘entirely of small connective tissue cells. Sections of the young 
tadpoles of Bufo lentiginosus show that the germ-cells are 
never found anterior to Bidder’s organ in this amphibian. In 
Bufo the germ-cells are not derived from peritoneal cells but 
from undifferentiated embryonic tissue. It hardly seems prob- 
able, therefore, that a mass of cells having a different origin 
from the germ-cells and totally unlike them in structure ever 
belonged to the sex-gland proper at any period in the history 
of the race. In very young tadpoles the cells which are to 
develop into the fat body form a forward extension of the 
genital ridge, but this does not necessarily indicate that they 
were primarily sex-cells. I am strongly inclined to believe 
that the peritoneal cells which form the fat body have second- 
arily come into connection with the anterior end of the genital 
ridge and that Bidder’s organ marks the extreme anterior 
boundary of the sex-gland. If this be true, then Marshall's 
theory is untenable since the cells forming the fat body are 
not germ-cells, and even Marshall himself believes that the 
cells of Bidder’s organ are degenerate ova. 
There is a third possibility regarding the origin of Bidder’s 
organ which may be suggested, although little can be said in 
its favor. Bidder’s organ may, perhaps, be the remains of a 
primitive sex-gland which was functional when the Bufonidae 
were sexually mature in their larval state, as is the condition 
of the Axolotl at the present time. On this assumption the 
ovary and testis are structures secondarily acquired when the 
reproductive activity became manifested at a later period in 
the life of the individual. The similarity in the appearance of 
the cells of Bidder’s organ in both sexes and their resemblance 
to ova can be accounted for on the supposition that, as the 
