104 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Reaumur cut off the "tails" of crayfishes in various places, but there was never 

 any reproduction of these parts, and the animals invariably died after a few days. It 

 sometimes happens that a lobster loses a part of its "tail," and the accident probably 

 results fatally in most cases, but not always, according to the statement of Mr. Thomas 

 Barton, who is employed at the lobster pound at Viual Haven, Maine. He says that 

 in the winter of 1892-93 he caught several lobsters with the tail-fan and the last one 

 or two joints of the "tail" gone, apparently bitten off. There was a scar where the 

 wound had healed, but no sign of a regenerated tail. 



Chantran (38) says of the crayfish that the antenna? are regenerated in the period 

 between two successive molts, while three molts are required to restore the other 

 appendages. In the first year of life, seventy days, according to this observer, are 

 necessary for the generation of new limbs. The adult female requires 3 to 4 years, 

 the male li to 2 years to repair its limbs, and we are told that the adult male molts 

 twice and the female but once in the year. 



Chantran has also some interesting notes on the regeneration of the eyes in the 

 crayfish (40). This process takes place more or less normally and rapidly according 

 to the age of the animal. When the eyes are cut off in October, at the end of the 

 season of molting, there is no new growth apparent until the following May. At that 

 time a series' of molts is begun, and by July, nine months after excision, the eyes are 

 regenerated. If the eyes are operated on in the molting season, the regenerative 

 processes are disturbed. In his experiments about one-half of the optic peduncle 

 was cut away; with total excision of the peduncle the eye was never regenerated. 



Goodsir (80) explains the production of new limbs from the basipodite in the 

 following way: 



A small glaudular like body exists at this spot in each of the limbs, which supplies the germs of 

 future legs. This body completely fills up the cavity of the shell for the extent of about half an inch 

 in length. The microscopic structure of this glandular-like body is very peculiar, consisting of a 

 great number of large nucleated cells, 'which are interspersed throughout a fibro-gelatinous mass. A 

 single branch of each of the great vessels, accompanied by a branch of nerve, runs through a small 

 foramen near the center of this body, but there is no vestige either of muscle or tendon, the attach- 

 ments of which are at each extremity. In fact, this body is perfectly defined and can be turned out 

 of the shell without being much injured. When the limb is thrown off the blood vessels and nerve 

 retract, thus leaving a small cavity in the new-made surface. [See the account given by Fredericq.] 

 It is from this cavity that the germ of the future leg springs, and it is first seen as a nucleated cell. 



These statements, some of which — as the existence of a glandular body and the 

 origin of the limb from a nucleated cell — are entirely erroneous, will be discussed 

 hereafter (see pp. 107, 108). 



REGENERATION OF LARGE OHELIPEDS. 



The regeneration of the large chelipeds in the fourth and fifth larval stages is 

 essentially the same as in the adults. The external changes are illustrated by figs. 

 176, 182, and may be described as follows: At the moment the limb is broken off blood 

 immediately oozes out and coagulates, forming a dense crust over the stump. In a 

 short time a small white papilla which represents the rudiment of the new limb appears 

 in the midst of the brown, hardened clot, fig. 176, plate 44. This papilla continues to 

 grow, independently of the molting process, though covered with a cuticular mem- 

 brane, until a miniature appendage is formed. The papilla lengthens, and gradually 

 the constrictions which mark the future joints of the new limb make their appear- 

 ance. At first colorless, the new appendage becomes bright, transparent red, with 



