Note that this version from Crane's Italian Popular Tales is taken from Straparola's The Facetious Nights, often titled 'Constantino Fortunato.'

Soriana dies and leaves three sons: Dusolino, Tesifone, and Constantine the Lucky, who, by virtue of a cat, acquires a powerful kingdom.

THERE was once in Bohemia a very poor lady named Soriana, who had three sons: one was called Dusolino, the other Tesifone, and the third Constantine the Lucky. She owned nothing valuable in the world but three things: a kneading-trough, a rolling-board, and a cat. When Soriana, laden with years, came to die, she made her last testament, and left to Dusolino, her eldest son, the kneading-trough, to Tesi fone the rolling-board, and to Constantine the cat. When the mother was dead and buried, the neighbors, as they had need, borrowed now the kneading-trough, now the rolling-board; and because they knew that the owners were very poor, they made them a cake, which Dusolino and Tesifone ate, giving none to Constantine, the youngest brother. And if Constantine asked them for anything, they told him to go to his cat, which would get it for him. Wherefore poor Constantine and his cat suf fered greatly. Now the cat, which was enchanted, moved to compassion for Con stantine, and angry at the two brothers who treated him so cruelly, said: “Constan tine, do not be downcast, for I will provide for your support and my own.” And leav ing the house, the cat went out into the fields, and, pretending to sleep, caught a hare that passed and killed it. Thence, going to the royal palace and seeing some of the courtiers, the cat said that she wished to speak with the king, who, when he heard that a cat wished to speak to him, had her shown into his presence, and asked her what she wished. The cat replied that her master, Constantine, had sent him a hare which he had caught. The king accepted the gift, and asked who this Constantine was. The cat replied that he was a man who had no superior in goodness, beauty; and power. Wherefore the king treated the cat very well, giving her to eat and drink bountifully. When the cat had satisfied her hunger, she slyly filled with her paw (unseen by any one) the bag that hung at her side, and taking leave of the king, car ried it to Constantine. When the brothers saw the food over which Constantine exulted, they asked him to share it with them; but he refused, rendering them tit for tat. On which account there arose between them great envy, that continually gnawed their hearts. Now Constantine, although handsome in his face, nevertheless, from the privation he had suffered, was covered with scabs and scurf, which caused him great annoyance. But going with his cat to the river, she licked him carefully from head to foot, and combed his hair, and in a few days he was entirely cured.

The cat (as we said above) continued to carry gifts to the royal palace, and thus supported her master. But after a time she wearied of running up and down so much, and feared that she would annoy the king’s courtiers; so she said to her mas ter: “Sir, if you will do what I order, I will make you rich in a short time.” “How?” said her master. The cat replied: “Come with me, and do not ask any more, for I am ready to enrich you.” So they went together to the stream, which was near the royal palace, and the cat stripped her master, and with his agreement threw him into the river, and then began to cry out in a loud voice: “Help! Help! Messer Constantine is drowning.” The king hearing this, and remembering that he had often received presents from him, sent his people at once to aid him. When Mess er Constantine was taken out of the water and dressed in fine clothes, he was taken to the king, who received him cordially, and asked him why he had been thrown into the river. Constantine could not answer for grief; but the cat, which was always at his side, said: “Know, 0 king, that some robbers learned from spies that my master was loaded with jewels, which he was coming to present to you. They robbed him of all, and threw him into the river, thinking to kill him, but thanks to these gentlemen he has escaped from death.” The king, hearing this, ordered that he should be well cared for; and seeing that he was handsome, and knowing him to be wealthy, he concluded to give him Elisetta, his daughter, for a wife, endowing her with jewels and most beautiful garments. After the wedding festivities had been ended, the king had ten mules loaded with money, and five with costly apparel, and sent his daughter to her husband’s home, accompanied by a great retinue. Constantine, seeing that he had become so wealthy and honored, did not know where to lead his wife, and took counsel with his cat, which said:
“Do not fear, my master, for we shall provide for everything.” So they all set out gayly on horseback, and the cat ran hastily before them; and having left the com pany some distance behind, met some horsemen, to whom she said: “What are you doing here, wretched men? Depart quickiy, for a large band of people are coming, and will take you prisoners. They are near by: you can hear the noise of the neigh ing horses.” The horsemen said in terror: “What must we do, then?” The cat replied: “Do this,—if you are asked whose horsemen you are, answer boldly, Messer Constantine’s, and you will not be molested.” Then the cat went on, and found a large flock of sheep, and did the same with their owners, and said the same thing to all those whom she found in the road. The people who were escorting Elisetta asked the horsemen: “Whose knights are you,” and “whose are so many fine flocks?” and all with one accord replied: “Messer Constantine’s.” Then those who accompanied the bride said: “So then, Messer Constantine, we are beginning to enter your territory.” And he nodded his head, and replied in like manner to all that he was asked. Wherefore the company judged him to be very wealthy. At last the cat came to a very fine castle, and found there but few servants, to whom she said: “What are you doing, good men; do you not perceive the destruction which is impending?” “What?” asked the servants. “Before an hour passes, a host of sol diers will come here and cut you to pieces. Do you not hear the horses neighing? Do you not see the dust in the air? If you do not wish to perish, take my advice and you will be saved. If any one asks you whose this castle is, say, Messer Con stantine’s.” So they did, and when the noble company reached the handsome cas tle they asked the keepers whose it was, and all answered boldly Messer Constan tine the Lucky’s. Then they entered, and were honorably entertained. Now the castellan of that place was Signor Valentine, a brave soldier, who, a short time before, had left the castle to bring home the wife he had lately married; and to his misfortune, before he reached the place where his wife was he was overtaken on the way by a sudden and fatal accident, from which he straightway died, and Con stantine remained master of the castle. Before long, Morando, King of Bohemia, died, and the people elected for their king Constantine the Lucky because he was the husband of Elisetta, the dead king’s daughter, to whom the kingdom fell by right of succession. And so Constantine, from being poor and a beggar, remained Lord and King, and lived a long time with his Elisetta, leaving children by her to succeed him in the kingdom.

Crane, Thomas Frederick. Italian Popular Tales. Boston: Houghton Mifflin Company, 1885. 
Amazon.com: Buy the book in hardcover orpaperback.