with reference to the said figures , the simulation for example of the growth of a limb is obtained with the particular ( 1 ) in thermoplastic in the form of a tube with a restriction of the internal section supporting a spring ( 2 ) at the part ( 1 . 1 ) and supporting the gluing to the remaining part of the limb at the part 1 . 2 , whereas at the other extremity 1 . 3 it is tapered to obtain an aesthetically correct coupling with the particular 3 , which represents the sliding part of the extensible arm , because , at extremity 3 . 1 , it allows the reaction with the spring 2 , which is compressed or released according to whether the cable 4 , connected in 3 . 2 , or fixed with a section of yielding metal cylinder 3 . 2 a , appropriately deformed by squashing , is extended or withdrawn . extension or withdrawal of the cable 4 takes place by action of the pulley 5 , with a fixing hole 5 . 1 for the cable 4 , governed by the motor 6 , controlled by an electronic circuit 7 powered by an accumulator 8 . the particular 3 has a joint 3 . 3 for connection by joint or gluing of the front part of the extensible organ 3 to the rest of the limb . according to this present invention as shown in fig1 in a toy that requires elongation of the limbs or other parts of the body , for example a doll , there is an electronic control circuit ( 7 ) which recognises whether the user has used , touched or moved the toy . this requisite is important , because if the user relates to the toy , the growth that the toy &# 39 ; s mechanisms make available becomes visible almost immediately . the electronic circuit 7 has , as said , a device for recording the number and frequency of the shakes the toy receives . these are the parameters utilised to give consent to growth . that happens because , in the presence of the events described , the electronic circuit 7 sends a command and the necessary energy , taken from the accumulator 8 , to the electric motor 6 — connected by the electric wires 6 . 1 — which starts up and drives the reducer 8 a , connected through pulley 5 and the cables 4 to the extremity of the extensible organ 3 , permitting the amount of extension provided for . the electric motor 6 , following consent from the electronic circuit 7 , rotates and draws with it the cams 5 . 1 a positioned on the disc 5 a or the pulley 5 of fig2 which — see fig2 . 1 — slackening the cable 4 . the spring 2 is no longer compressed and expands , moving the particular 3 , providing evidence of the lengthening of the limb . at that point the doll &# 39 ; s clothes have become short and tight and the user has to change them , thus meeting a natural need which will be learned quickly and indelibly . the electronic circuit is calibrated in such a way that if , for example , the toy is not used for 100 hours , the limbs and other parts of the body shrink and retract to the original position of fig1 showing an evident and apparent slovenly aspect , because the clothes have suddenly become too large and too long . fig3 shows a preferential section of the bust in which it can be seen that the device of fig2 and 2 . 1 consists of an outer piece 9 and an inner piece 3 which are connected by slotting in to the lower and upper part of the bust respectively and keep the spring 2 compressed thanks to the action described above of the cable 4 . they represent a solution for lengthening and shortening the limbs and other parts of the toy &# 39 ; s body . again in fig3 one sees an alternative solution for extension of the bust by which the lengthening and shortening of this part of the body is obtained by the spring 2 a , which is compressed between the upper and lower parts of the bust thanks to the reaction points 12 . 1 and 15 . 1 , when the lower part is connected directly to the pulley 5 . through the weakly elastic cable 4 a fixed to the support 12 . 2 . this is possible because the two sections of the bust slide over each other like the sections of a telescope , like the particulars indicated in fig2 and 2 . 1 , and also because the distance the thread moves to ensure the functioning is appropriately determined through idler pins and bearings to reduce friction and hence the size of the motor . in fig3 we see the result achieved for the pelvis . in fig1 the same extension elements of fig2 — jointed or glued in the points 15 . 2 and 15 . 3 through the cable 4 connected to the pulley 5 — keep the spring 2 compressed or determine an extended position for it , managing to show the extension envisaged for the neck , too . fig4 shows the reason why the legs connected with thread 4 lengthen more that the arms . as can be seen , the pulleys differ in their radius and pulley 20 has a greater radius than pulley 21 . for the same number of rotations , therefore , cable 4 is wrapped less around pulley 20 than it is around pulley 21 . when , for the reasons described , the electronics 8 give permission to slacken cable 4 , the pulley moves through an fixed angle , whereas the two cables travel different distances . fig5 shows a pulley 5 formed of 3 pulleys 20 , 21 and 22 coupled in such a way as to create different extensions for the arms , legs and neck , or vice versa ; as can be seen this pulley also presents the wedge 24 . fig7 . 1 sketches the breast of a doll seen from the side in longitudinal section performed on the outer casing . the same view but from above appears in fig7 . from both the figures one notes that pulley 5 is fitted with wedge 24 . when it rotates in the release stage , the wedge pushes the mobile plate 25 which is held in the retracted position by the action of the spring 26 positioned around the pin 27 solid with the outer casing and held by the locking ring 28 . when the motor 8 has consent to release the cables 4 , these lengthen , because the pulley 5 rotates and in the presence of the wedge 24 it will act on the mobile plate 25 , which overcomes the reaction of the spring 26 , allowing the mobile plate 25 to run , guided by the pins 27 until the wedge 2 and the mobile plate 25 reach the position indicated in fig8 and 8 . 1 , where the breast 29 is shown , connected to the mobile plate 25 it has emerged fully from the aperture 30 . fig6 shows a wedge 24 placed radially on the outside of the pulley 5 , because in some cases the motor could work inclined 90 ° with its axis parallel to the mobile plate 25 as indicated in fig9 and then , to push the mobile plate 25 , only the position of the wedge in relation to the pulley changes . it can be observed from fig2 that when all the components have been mounted , the spring 2 is mounted , with the cable 4 running within it , and then the spring 2 is allowed to run within the piece 9 and then the pieces 9 and 3 are brought into position , connecting the cable to the pulley 5 at point 5 . 1 to make it wrap around the pulley . the operations described are repeated for the two arms , the two legs and the neck and the front halves of the bust are mounted . the accumulator and controlling electronics had been mounted earlier , so that the toy is then ready for use with few and simple operations .