Chapter III— MOLTING AND GROWTH. 



EARLIER OBSERVATIONS 



The process of molting, which makes growth possible to the arthropod, is of such 

 interest and importance that it deserves very careful attention. There is much to be 

 added to our knowledge of this subject in the lobster, and I shall deal with it at 

 full length. Aristotle knew very well that crabs and lobsters shed their shells (The 

 History of Animals, Book vni, c. xix), although his observations were not accurate; 

 but the fact was forgotten and finally denied altogether. 



It is only necessary to go back to the beginning of the last century (in 1712) to 

 find Reaumur (161) demonstrating that the river crayfish periodically cast its shell, 

 yet iu the early part of the seventeenth century, a hundred years before, Olaus 

 Wormius, according to Couch (47), speaks of the molting of crabs as a thing not to 

 be doubted. 



The regeneration of the lining of the stomach of the crayfish was reported by 

 Van Helmont, but this writer's reputation did not lend much weight to the statement 

 until it was confirmed in 1709 by Geoffroy (74). 



To that marvelonsly acute observer, Reaumur, we are indebted for the best account 

 of the exuviation of the crayfish. He took crayfishes which appeared to be ready to 

 molt and placed them in jars of water in his museum and watched them carefully. 

 Others he put into boxes, the bottoms of which were pierced with holes, and moored 

 them in the river Marne, which flowed past his garden. The crayfishes in the river 

 were under more favorable conditions than those kept in the house, and molted more 

 frequently iu consequence. He gives a very circumstantial account of the external 

 process of molting in the crayfish, which took place in June, July, and August. The 

 time occupied in the final act of casting the shell by crayfishes kept in the river was 

 from seven to fifteen minutes, while those in the house often struggled for several 

 hours before they were free. Sometimes they died in the operation, especially the 

 young ones. Some would lie on their sides, some on their bellies or backs, and in the 

 latter case he observed that they frequently died. 



However, as Couch remarked, Reaumur's paper produced so little effect that 

 when, many years later (1756), Peter Collinson communicated some cursory remarks 

 on this subject to the Royal Society, his account of the molting of the crab was received 

 with so much doubt that his second paper was chiefly employed in furnishing evidence 

 of the fact. 



Observations on the molting of the higher Crustacea have since been made by 

 Couch (45, 46, ^7),Gosse (81), Chantran (37), Max Braun (22), Vitzou (197), Sars (176), 

 Hyatt (101), Brook (26), and others. The histological changes involved in the molting 



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