(Frederic), one of the most eminent anatomists of which Holland can boast, was born at the Hague in 1638. After making great progress at home, he repaired to Leyden, and there prosecuted the study of anatomy and botany. He studied next at Franeker, where he obtained the degree of doctor of physic. He then returned to the Hague; and marrying in 1661, dedicated his whole time to the study of his profession. In 1665 he published a treatise, entitled Dilucidatio valvularum de variis lymphaticis et lacteis; which raised his reputation so high, that he was chosen professor of anatomy at Amsterdam. This honour he accepted with the more pleasure, because his situation at Amsterdam would give him easy access to every requisite help for cultivating anatomy and natural history. After he settled in Amsterdam, he was perpetually engaged in dissecting and in examining with the most inquisitive eye the various parts of the human body. He improved the science of anatomy by new discoveries; in particular, he found out a way to preserve dead bodies many years from putrefaction. His anatomical collection was curious and valuable. He had a series of foetuses of all sizes, from the length of the little finger to that of a new born infant. He had also bodies of full grown persons of all ages, and a vast number of animals almost of every species on the globe, besides a great many other natural curiosities. Peter the Great of Russia, in his tour through Holland in the year 1698, visited Ruyseche, and was so charmed with his conversation, that he passed Ruytch, passed whole days with him; and when the hour of departure came, he left him with regret. He set so high a value on Ruytch's cabinet of curiosities, that when he returned to Holland in 1717, he purchased it for 30,000 florins, and sent it to Peterburgh.

In 1685 he was made professor of medicine, an office which he discharged with great ability. In 1728 he got his thigh-bone broken by a fall in his chamber. The year before this misfortune happened he had been deprived of his son Henry, a youth of talents, and well skilled in anatomy and botany. He had been created a doctor of physic, and was supposed to have assisted his father in his discoveries and publications. Ruytch's family now consisted only of his youngest daughter. This lady had been early inspired with a passion for anatomy, the favourite science of her father and brother, and had studied it with success. She was therefore well qualified to assist her father in forming a second collection of curiosities in natural history and anatomy, which he began to make after the emperor of Russia had purchased the first. Ruytch is said to have been of so healthy a constitution, that though he lived to the age of 93, yet during that long period he did not labour under the infirmities of disease above a month. From the time he broke his thigh he was indeed disabled from walking without a support; yet he retained his vigour both of mind and body without any sensible alteration, till in 1731 his strength at once deserted him. He died on the 22d of February the same year. His anatomical works are printed in 4 vols 4to.

The style of his writings is simple and concise, but sometimes inaccurate. Instruction, and not ostentation, seems to be his only aim. In anatomy he undoubtedly made many discoveries; but from not being sufficiently conversant in the writings of other anatomists, he published as discoveries what had been known before. The academy of sciences at Paris in 1727 elected him a member in place of Sir Isaac Newton, who was lately deceased. He was also a member of the Royal Society of London.

RYTER (Michael Adrian), a distinguished naval officer, was born at Flessingue, a town of Zealand, in 1607. He entered on a sea-faring life when he was only 14 years old, and was first a cabin-boy. While he advanced successively to the rank of mate, master, and captain, he acquainted himself with ability and honour in all these employments. He repulsed the Irish, who attempted to take Dublin out of the hands of the English. He made eight voyages to the West Indies and ten to Brazil. He was then promoted to the rank of rear-admiral, and sent to assist the Portuguese against the Spaniards. When the enemy came in sight, he advanced boldly to meet them, and gave such unquestionable proofs of valour as drew from the Portuguese monarch the warmest applause. His gallantry was still more conspicuous before Salee, a town of Barbary. With one single vessel he sailed through the roads of that place in defiance of five Algerine Corsairs who came to attack him.

In 1653 a squadron of seventy vessels was dispatched against the English under the command of Van Tromp. Ruyter, who accompanied the admiral in this expedition, seconded him with great skill and bravery in the three battles which the English so gloriously won. He was afterwards stationed in the Mediterranean, where he captured several Turkish vessels. In 1659 he received a commission to join the king of Denmark in his war with the Swedes; and he not only maintained his former reputation, but even raised it higher. As the reward of his services, the king of Denmark ennobled him and gave him a pension. In 1661 he run aground a vessel belonging to Tunis, released 40 Christian slaves, made a treaty with the Tunisians, and reduced the Algerine corsairs to submission. His country, as a testimony of her gratitude for such illustrious services, raised him to the rank of vice-admiral and commander-in-chief. To the latter dignity, the highest that could be conferred upon him, he was well intitled by the signal victory which he obtained over the combined fleets of France and Spain. This battle was fought in 1672 about the time of the conquest of Holland. The fight was maintained between the English and Dutch with the obstinate bravery of nations which were accustomed to dispute the empire of the main. Ruyter having thus made himself master of the sea, conducted a fleet of Indiamen safely into the Texel; thus defending and enriching his country, while it was become the prey of hostile invaders. The next year he had three engagements with the fleets of France and England, in which, if possible, his bravery was still more distinguished than ever. D'Estrees the French vice-admiral wrote to Colbert in these words: "I would purchase with my life the glory of De Ruyter." But he did not long enjoy the triumphs which he had so honourably won. In an engagement with the French fleet off the coast of Sicily, he lost the day, and received a mortal wound, which put an end to his life in a few days. His corpse was carried to Amsterdam, and a magnificent monument was there erected by the command of the states-general. The Spanish council bestowed on him the title of duke, and transmitted a patent inviting him with that dignity; but he died before it arrived.

When some person was congratulating Louis XIV. upon De Ruyter's death, telling him he had now got rid of one dangerous enemy; he replied, "Every one must be sorry at the death of so great a man."