(38) In the gutters . . . --Heb., in the troughs at the watering-places. So virtually all the versions; and see Exodus 2:16, where the word rendered here "gutters" is rightly translated troughs. The idea that there were gutters through which to pour the water into the troughs is utterly modern, but all travellers describe the fixed troughs put for the convenience of the cattle round the wells.

Verse 38. - And he set the rods which he had pilled before the flecks in the gutters (רִחָטִים; literally, the canals or channels through which the water ran, from a root signifying to run) in the watering troughs (שִׁקֲתות, i.e. the troughs which contained the water, to which the animals approached) when the flocks came to drink, that they should conceive (literally, and they became warm, in the sense expressed in the A.V.) when they cams to drink - this was Jacob's first artifice to overreach Laban.

30:25-43 The fourteen years being gone, Jacob was willing to depart without any provision, except God's promise. But he had in many ways a just claim on Laban's substance, and it was the will of God that he should be provided for from it. He referred his cause to God, rather than agree for stated wages with Laban, whose selfishness was very great. And it would appear that he acted honestly, when none but those of the colours fixed upon should be found among his cattle. Laban selfishly thought that his cattle would produce few different in colour from their own. Jacob's course after this agreement has been considered an instance of his policy and management. But it was done by intimation from God, and as a token of his power. The Lord will one way or another plead the cause of the oppressed, and honour those who simply trust his providence. Neither could Laban complain of Jacob, for he had nothing more than was freely agreed that he should have; nor was he injured, but greatly benefitted by Jacob's services. May all our mercies be received with thanksgiving and prayer, that coming from his bounty, they may lead to his praise.And he set the rods which he had pilled before the flocks,.... Opposite them, in the view of them:

in the gutters in the watering troughs, when the flocks came to drink; that is, in places of water, where troughs or vessels were made, into which the water ran convenient for the cattle to drink out of; and here he placed his party coloured rods right over against the flocks:

that they should conceive when they came to drink; as it was most likely they should when they were together at the water, and had refreshed themselves with it; and being "heated" (q), as the word signifies, with a desire of copulation, might conceive in sight of the above rods; which were set to move upon their imagination at the time of their conception, in order to produce cattle of different colours; to which no doubt he was directed of God, and it had, through his blessing, the wished for success, as follows:

(q) "incalescebant", Montanus, Vatablus, Drusius; "ut incalescerent", Junius & Tremellius.