May 1676

In yet another unpublished letter to Oldenburg, dated May 29 (AB 23), Leeuwenhoek responds to Grew's response, which was not published until the middle of the summer. The letter opens:

I received your honoured letter of the 4th inst. in good order, from which I learned that my observations on the hair do agree sufficiently with those of Mr. Hooke on the same subject, which pleases me very much. Also that you communicated my trifling observations set forth in my letter of April 21st to Doctor Grew; I thank this gentleman for remembering me; please give the said gentleman my best regards, and tell him that ...

What follows is a long and respectful point-by-point account of where they disagreed and where they agreed. Looking back, we can see that each was correct on some point, and each was wrong on others.

Thus, the letter from Oldenburg on May 4 must have contained a copy or at least a detailed summary of the Grew's response, which itself was not published until months later, without any of the counter-response from Leeuwenhoek's May 29 letter. Oldenburg's heads-up to Leeuwenhoek is another example of the scientific community's collegial norms forming.

It took him three weeks to respond, during which time he was beginning his daily observations of living creatures in water. He was also conducting the experiments that he recounted in the letter to Boyle in July.

At this point, only three of Leeuwenhoek's dozen previous letters had been published. The letters to him from Oldenburg have not survived, but we can see from the letters that he was eager to engage other scientists and willing to change his ideas. In other words, he was open to the review of his peers.

We can also imagine how he pondered the fact that for two years, most of his interesting observations had not been published and would, as far as he knew, remain forever buried in a pile on Henry Oldenburg's desk. In fact, it would be another two hundred and fifty years before they would be published, in 1930.

Experiments beginning in May
Infusion preparation start end duration observation
Ginger bruised ginger pieces in snow water in tea cup May 6 June 12 5 weeks 96 - 106
Clove 36 cloves in 21 oz rain water with no animals May 17 Sept 19 18 weeks 107 - 127
Rain 2 rain off slate roof in leaden gutters in glass May 26     2
Rain 3   May 26 May 31 5 days 3 - 5
Pepper 3 1/3 oz whole pepper pounded in teacup with 2 ½ oz rainwater, added water from Pepper 2 May 26 June 12 3 weeks 51 - 60



Observations in May
Date infusion findings quantity notes obs #
May 3 Pepper 2 nothing   added snow water 33
May 4 Pepper 2 nothing     34
May 5 Pepper 2 nothing     35
May 6 Pepper 2 bacilli very many   36
May 6 Ginger     Prepared bruised ginger pieces in snow water in a tea cup. 96
May 7 Pepper 2 bacilli still greater numbers   37
May 10 Pepper 2     added snow water 38
May 13 Pepper 2 little animals, as before     39
May 14 Pepper 2 little animals, as before     40
May 14 Ginger daily observation; no creatures     97
May 17 Clove     Prepared 36 cloves in 21 oz rain water with no animals. 107
May 18 Pepper 2     added snow water 41
May 23 Pepper 2 little animals as before, Colpidium colpoda     42
May 24 Pepper 2 Colpidium much greater numbers; thousands in one drop   43
May 25 Pepper 2 Colpidium, thread bacteria still more   44
May 25 Clove no living creatures     108
May 26 Rain 2 ciliates   saw them right away and wondered whether they might not have been bred in the leaden gutters 2
May 26 Rain 3 irregular earthy particles   thus no earthy particles would be splashed into the said dish by the falling of the rain at that spot 3
May 26 Pepper 2 Colpidium 6 or 8,000 in one drop   45
May 26 Pepper 2 no Colpidium but vorticella     46
May 26 Pepper 3     Prepared 1/3 oz whole pepper pounded in teacup with 2 ½ oz rainwater, added water from Pepper 241 51
May 27 Pepper 2 no very little animalcules but vorticella greater number   47
May 28 Pepper 2 same fewer    
May 29 Ginger daily observation, finally some cyclidium      
May 30 Rain 3 Monas very few    
May 30 Pepper 2 same fewer added snow water  
May 30 Ginger Bobo 25 times more    
May 31 Rain 3 little animals more    
May 31 Ginger aforesaid little animals much greater, several thousand in one drop    

Snow water decanted in the summer was the purest water available.