ON THE BRITISH BDBIOPHTHALMA. 43 



they are afterwards produced. Our observations have not been pursued 

 upon those species which are supplied with an abundant brush of hair, but 

 still it would appear, that if the remark be correct when the hairs are few, it 

 would lead to the same result where they are abundant. It is certainly 

 capable of demonstration, even before moulting, for we have repeatedly 

 observed the new hair attached to the new skin while examining specimens 

 under the microscope, where the second layer of similarly furnished integu- 

 ment is distinctly visible beneath the outer; and it has always appeared 

 to us, though contrary to anticipation, that the new materials (hairs, spines, 

 &c.) are not developed within each corresponding hair, spine, tooth, &c., 

 since they are visible within the integument as a second armature. 



This remark is particularly verified by the teeth on the maxillae ; this may 

 probably be here induced by their commonly forked character, which might 

 cause an injury, should they have to be withdrawn from similarly formed 

 organs. This is a fate that not unfrequently happens to the branchial sacs. 

 We have seen one of these last remain within the old tunic of the cast skin, 

 it having been torn from the parent during the process of moulting, owing 

 to the narrow neck of the sac ; but which by analogy, we may infer, is again 

 replaced by a process of repair, common to the whole class, but which has 

 most frequently been observed in the higher types of Crustacea. 



On the reproduction of lost parts. — The power of animals to restore to its 

 normal character a new limb or organ, is nowhere so visibly illustrated as in 

 this great class. The manner in which it is carried into effect has been 

 described by Dalyell, Goodsir, and others (including a short paper of our 

 own in the ' Annals of Natural History' for 1850, as well as the British Asso- 

 ciation Reports for the same year); but these labours have chiefly been 

 directed to the higher orders of Crustacea, among which it has been shown, 

 that upon the infliction of an injury upon any giyen member, the whole limb 

 is immediately forcibly dislocated and thrown off. This is always done at 

 the articulation between the coxa and the next succeeding joint. 



The wound that is caused by this sudden rupture of parts is naturally 

 stanched by a thin membrane which instantly shows itself as the immediate 

 result, and it appears not to be impossible, that its formation, which must be 

 very sudden, may be the amputating power. 



Observers have generally added as an appendage to the above curious fact 

 in nature, that it is exceedingly fortunate that Crustacea have this power of 

 voluntary amputation of their members at a given spot, for otherwise, enclosed 

 as they are in a most unyielding dermal case, they must, upon being wounded, 

 of necessity bleed to death. 



In all the natural sciences there is nothing more likely to lead to error 

 than deductions based upon negative evidence. That an animal would bleed 

 to death under such circumstances would appear an extremely probable 

 hypothesis ; but in answer to it, the whole of the order of the Amphipoda 

 appear to want the pow er of the dislodgement of any of the limbs, yet they 

 do not die upon being so wounded. 



If a leg be cut off, or any part injured, the wound appears shortly after to 

 cicatrize over with a black scar ; but as far as our opportunities, which have 

 not been inconsiderable, have enabled us to judge, the member is never 

 thrown off. 



That a limb upon being lost is capable of being reproduced, is, we believe, 

 correct, but the injured limb is not thrown off to facilitate the reproduction. 



We presume, that when the animal moults the skin, the remaining portion 

 of the injured member may be thrown off with it, and the new limb com- 

 mences reproduction at that or some earlier period ; but not having been 



