8 



Leiden, but the family was occasionally attacked by malaria. Derk, 

 who was still ailing, was nevertheless able to devote himself once more 

 to the education of his children, in which occupation he was sometimes 

 assisted by the eldest son, Frederik. As befitted a minister's daughter, 

 the mother gave her children a Christian upbringing. On Sunday mor- 

 nings the father used to read to them from a translation of Heinrich 

 Zschokke's "Stunden der Andacht" ("Devotional Hours") which 

 made a lasting impression upon them. Every morning, too, the mo- 

 ther used to read something to them from the Bible, and made the 

 children learn psalms and hymns by heart. She herself went to church 

 frequently. 



It is worth mentioning that when Martinus was 10 or 11 years 

 old, he was subject to fits; for some time he was so seriously ill that 

 his parents feared for his life. In those years a small legacy from an 

 aunt of Martinus' mother brought a considerable relief. The family 

 was a little better off now. They had never lived above their income. 

 The mother, the soul of the family, had by her good housewifely ma- 

 nagement avoided getting into debt, but at the same time she had seen 

 to it that the children should not go short of necessities. They had ne- 

 ver actually suffered want, and indeed they had no real notion of the 

 cares that weighed down their parents. But the financial difficulties 

 of the parents prevented them, although people of culture and good 

 standing, from having that intellectual contact with the outer world 

 which would have assisted the social development of their children. In 

 all probability this contributed to the inclination to solitariness of the 

 youngest son who, like his sister Johanna, was fundamentally gentle 

 and timid. Frederik, the eldest of the four, was a sturdy boy; and on 

 the lonely winter evenings, when the father was at his office, the mo- 

 ther was always glad if Frederik was at home. Frederik was an intel- 

 ligent lad, but, through lack of means, did not get the best training. 

 Yet, whenhe was 18 years old, and had to join the army as a conscript, 

 the family managed to take a substitute for him. Quite early he was 

 apprenticed in the office of a surveyor in order to qualify for admis- 

 sion to the cadastral survey, and later he came to be a surveyor. 



In 1863 Derk was transferred back to Haarlem, and the family 

 went to live at the Nieuwe Gracht overlooking the Spaarne, Koude 

 Hoorn and Scheepmakersdij k. The children then were 18, 16, 14 and 

 1 2 years old respectively. Frederik was training for the assistant sur- 

 veyor examination, Henriëtte became a pupil-teacher, Johanna went 

 to school and studied for the elementary school teacher's examination, 

 and Martinus attended the elementary school of Master Knoop and 

 subsequently the "Hoogere Burgerschool" (secondary school) at 

 Haarlem, where Dr. E. van der Ven was head-master. Few recollec- 

 tions of that period remained with Professor Beijerinck in later life. 

 All he remembered was that it had been a miserable time for him. In 

 the elementary school the master once called upon him to teil the 



