316 Spiral Qrowlh of Appendages in Arthropoda. 



removed by an artificial cut, on the other hand, follows the 

 method of rectilinear growth [see Bordage, " Regcineration 

 des membres chez les Phasmidesapr^s des sections artiticielles" 

 (Ann. Soc. Entom. de France, p. 87, 189S)]. 



In the paper referred to, after having indicated that the 

 growth of self-mutilated limbs in course of rej)lacement takes 

 place with relatively remarkable speed, I added that, on the 

 contrary, in the case of parts of limbs artificially removed by 

 cutting it proceeds with the greatest slowness. The part, 

 however, in course of regeneration after artificial severance 

 having of necessity immediately after the next moult the same 

 diameter as the termination of the stump of greater or less 

 length remaining in place, it follows that growth in diameter 

 must be quite as rapid as in the Mantidie and Blattidee. It 

 is even sometimes as rapid as the growth in length * and 

 that exactly at the commencement of the regenerative process, 

 but at this period alone. Afterwards it slackens considerably 

 and follows the speed of growth in diameter of the whole 

 limb with which it is to be blended. 



]n this way the work of regeneration of a part of a limb 

 ■which has started, as is the rule, near the central portion of 

 the cut has already spread to the whole surface of the latter 

 before the rudiment of the limb has attained an appreciable 

 length. This rudiment possesses then the diameter of the 

 part of which it is a prolongation, and its insignificant length 

 does not compel it to coil upon itself under the protecting 

 cuticle, as would certainly happen if its growth in length were 

 rapid and if its diameter remained at the same time much 

 smaller than that of the stump which it must complete. It 

 can then stretch the thin cuticle before it during its whole 

 extension and grow rectilinearly. 



I have been able to determine that the same thing happens 

 sometimes in Orthoptera saltatoria following artificial division 

 carried out on the two front pairs of limbs either on the lower 

 part of the tibia or on the first joints of the tarsus in the 

 jumping-legs. Here, however, this result is not constant, as 

 in the Phasmidaj. It only follows in the case where, from 

 some cause or other, regeneration takes place with great 

 slowness. Otherwise the growth is spiral. 



We have, then, a second cause leading to the rectilinear 

 growth of a member in course of regeneration. It is proper 

 to add that in this case turgidity seems also to play a certain 

 part. 



* Thus I have determined that iu a liirva of Monandroptera inunca7is, 

 after tl\e moult, which occurred in the first place some time after the 

 artificial severance of a limb 2 millim. iu diameter at the point where 

 eectiou had been performed, the terminal projection formed by the part in 

 course of regeneration had itself scarcely reached 2 millim. in length. 



