ALPHEUS HYATT: MEMORIAL MEETING. 
419 
poda for this purpose. We often discussed their relationships, and 
our first published conclusions show what violence may be done to 
creatures in forcing them into relationships which have no existence 
in nature. Hyatt was always attracted to groups of animals which 
showed great individual variation correlated with external causes. 
This impelled him to take up the study of a most difficult group of 
creatures, the sponges. His “Revision of the North American 
Poriferae,” published as a memoir of the Boston society of natural 
history in 1877, is an instance of this impulse. In this memoir he 
showed the profound way in which he grasped the difficulties of 
this protean group. It Was this same impulse that led him to a 
minute study of the Achatinellidae of the Hawaiian islands, a group 
of land snails showing an infinite variety of color patterns. At the 
time of his death he was about starting for these islands to complete 
a series of investigations that he had carried on for several years. 
Much of the work had been done and, fortunately for science, his 
son-in-law. Doctor Mayer, has volunteered to complete the work. 
Hyatt’s investigation of the fossil fresh-water . shells found in a 
circumscribed area at Steinheim, near Stuttgart, was animated by a 
desire to ascertain if the same laws of growth and decay could be 
found in this group which was limited to a short period of time, as 
those laws of growth he had demonstrated in the Jurassic ammon¬ 
ites covering an immeasurable period of time. This memoir was 
published in 1880 and exhibits again the minute and painstaking 
manner in which he grasped an infinite mass of detail. Not 
content with studying the material of the Steinheim deposits which 
he was permitted to examine in various collections abroad, he visited 
the quarries and made new and extensive collections of the fossils in 
situ. 
That his principles of acceleration and retardation, his old age 
theory, and other views of the stages of life are not yet fully grasped, 
is true. Many have not understood them. Though they are all 
evolutionary, yet Darwin himself was perplexed. I may be per¬ 
mitted to give an extract from a letter which Darwin wrote to me 
concerning this very matter. In this letter he asks, “What is the 
meaning of Professor Cope’s and Hyatt’s views on acceleration and 
retardation ? I have endeavored and given up in despair an attempt 
to grasp their meaning.” Slowly, however, his views are being 
applied to the consideration of various groups of animals, notably by 
