Lost Characteristic 



to determine its exact course. My paper, " Senesence and Re- 

 juvenation," affords evidence of new facts proven by these ex- 

 periments. I believe I have thus won the right to oppose my 

 view to the pure speculations of Weismann. 

 ( To be continued.) 



LOST CHARACTERISTICS. 

 By Alpheus Hyatt. 



Dr. Minot having noticed, in the translation of his article 

 *' On Heredity and Rejuvenation," an accidental omission of 

 quotation of work done by paleontologists on the loss of char- 

 acteristics in the development of animals, has most courteously 

 asked me to follow his essay by an article dealing with this 

 question. I gladly avail myself of this opportunity on account 

 of the advantages offered where similar subjects can be con- 

 secutively treated from different points of view, and because 

 Dr. Minot's article, on account of his great and deserved repu- 

 tation in embryology, will reach the students of existing bio- 

 logical phenomena, and perhaps induce some of them to read 

 a connected publication. 



The loss of characteristics is not so readily observed by a 

 student of the biology of existing animals or neobiologist, as 

 by the paleobiologist or student of fossils, because the latter 

 necessarily deals with series of forms often persisting through 

 long periods of time, and is led, especially if he follow more 

 recent methods of research, to study these in great detail. The 

 observer of these remains is not, as is falsely imagined, limited 

 to fragments, but can and does work out of the hard matrix 

 the external skeletons or shells even of embryos, and can, in 

 the corals, brachiopoda, mollusca, echinodermata and even in 

 protozoa, follow the entire life history of these parts in the in- 

 dividual. He has also the further advantage of availing him- 

 self of the knowledge amassed by the neobiologist and neoem- 

 bryologist, the works of % Cope, Beecher, Schuehert, Gurley, 



