ENTOMOLOGY. 303 



though still inferior to the other legs : so also after the third ; but after the 

 fourth they were no longer distinguishable from the rest. 



The experiment as to Insects with complete metamorphoses was made 

 upon Vanessa urtica. Some of the true feet were cut off, entirely or in 

 part, in a number of Caterpillars before they were full grown. The leg cut 

 off was reproduced, in some of the younger ones, immediately after the 

 moult which remained to be undergone. Out of twenty-eight Caterpillars 

 the author obtained thirteen Butterflies. In four no trace of reproduction 

 was seen, or scarcely any ; in the rest it was pretty complete, the leg being 

 sometimes perfect but under-sized, sometimes the foot-joints shorter than 

 usual ; in one instance the shank was restored entire, but without the spines 

 at the end. 



From these experiments it appears that 1, reproduction of lost mem- 

 bers takes place also in Myriapoda and Insects with complete metamor- 

 phosis ; 2, it is simultaneous with the moulting. 



Rathke (Miiller's Arch. Anat. 1844, p. 27, pi. 2, f. 1-5) 

 has made observations on the development of the Mole- 

 cricket (Gryllotalpa vulgaris), which are of great and general 

 interest, bringing to light a new fact, that in the embryo of 

 an insect a temporary organ exists, which seems to be of the 

 nature of a gill. 



1. The egg increases by about a third in volume during the development 

 of the embryo, probably by imbibing water from the moist earth in which it 

 is deposited. The author has found the like to take place in the eggs of 

 other insects also, as Phryganese, and of many Crustacea. 2. The egg, 

 when newly excluded, shows two coats, the outer transparent (chorion), 

 the inner more delicate (membrana vitelli.) These are closely applied to 

 one another, and in like manner enfold the yelk, which is composed of sim- 

 ple cells and drops of grease. The embryo is formed at the circumference 

 of the yelk, so that this is at last completely contained within it. In the 

 second half of the vegetative period (frucht-lebeu) a clear fluid collects 

 between the embryo and the coats of the egg ; this is no water of absorp- 

 tion, for it contains much albumen, and coagulates on contact with water or 

 alcohol. It disappears when the embryo is at maturity. 3. The inner coat 

 is obliterated completely in the second half of the vegetative period, while 

 the outer one becomes thinner and more transparent. 4. The embryo gra- 

 dually takes such a curved form that the thorax is strongly bowed, and the 

 head bent in upon itself. The legs are so placed that thigh and shank com- 

 pose a sort of loop. 5. The integument of the abdomen is drawn into a 

 flatfish fold at the sides, where the row of spiracles is in course of formation. 

 G. Under this fold, and immediately behind the attachment of the third 



