Adding together all the hoppers listed above, we find that 637 individuals were reared in these experiments from 34 different pairs of adults; 394 were reared in complete isolation, and 243 under crowded conditions, but each crowd consisted of the progeny of one pair only. The majority of those isolated were placed in isolation on the day of hatching, but some first lived in a crowd for a week or two before being used to replace isolated individuals that had died.

Comparing the results in Tables XXI and XXII, we noted that the isolated hoppers acquired the solitaria characters, while those crowded tended to develop the gregaria characters, regardless of whether the parents had been gregaria or solitaria. Only two isolated hoppers from the pair L.p.352 showed gregaria characters, and one of these had lived in a crowd and had acquired gregaria characters before it was placed in isolation in its second instar. Table XXIII shows that crosses between gregaria and solitaria gave the same results.

In the second generation (Table XXIV) the progeny of the P1gregaria pair 352 reacted to isolation and crowding in the same way as all other hoppers, and the same was true of the F2 back-cross to gregaria (L.p.569).

Examining the hypothesis of Potgieter in the light of these experiments, we find that the data presented in Tables XXI to XXIV are in direct contradiction with the three phases enumerated above. Instead of giving a majority of gregaria, the matings of gregaria by gregaria produced both gregaria and solitaria according to the conditions under which the progeny were reared. According to the second thesis, the crossing of solitaria and gregaria should always result in a majority of gregaria, but Table XXIII shows that 90 isolated hoppers all became solitaria. Thirdly, the mating of solitaria with solitaria is supposed never to produce gregaria progeny; Table XXII shows that the progeny of these crosses developed gregaria characters when crowded and solitaria when isolated.