56 PATTEN. [Vor. XII. 
It should also be observed that in Figs. 102 and 103, much less 
clearly in Fig. 104, the embryos, beginning with the most perfect 
embryo, A, show increased concrescence and degeneration as we 
pass in a spiral to embryos Band C. This interesting fact will 
be discussed under the head of double and triple monsters. 
Change in Shape of Fused and Degenerating Appendages. 
When two appendages unite, they fuse at the base first, and 
the fusion extends from that point toward the apex. The 
resultant appendage is at first much longer and more slender 
than the unfused ones. It is also usually folded back and forth 
several times, and otherwise irregular in shape. It subsequently 
diminishes in length, and finally forms a minute, conical papilla 
arising from the centre of a saucer-shaped depression. The 
papilla then disappears, leaving a shallow depression that cannot 
be readily distinguished from the oesophagus or the fused 
dorsal organs. 
As a general rule the order in which fusion takes place is 
indicated by the length and coiling of the appendages. When 
there are several fused appendages visible, they show a gradual 
diminution in these characters from before backwards, as in 
Figs. 40, 44, 46, and 102. In rare cases the same characters 
are presented by all the fused appendages of a series as in 
Figs. 50 and 100. 
V. GENERAL PROGRESSIVE DEGENERATION. 
A careful study and comparison of many abnormal embryos 
of various ages and conditions indicates pretty clearly that 
most of the abnormalities are due to either a local or a 
general lack of formative energy. We picture to ourselves 
two sets of factors at work, the action of one being to increase 
the quantity and diversification of protoplasm, the other to 
reduce it to its lowest terms. The action of the first may 
temporarily prevail, but in the end the second factors are 
certain to prevent the work of the creative ones. 
