Clifford Dobell's labor of love: Antony van Leeuwenhoek and his 'little animals'

Dear Reader: …meet Mr van Leeuwenhoek and shake him by the hand and hearken to what he has to say.  When you have done that, you will not only know the true meaning of that misused term 'scientific research', but you will also realize that you have already gone further along the path of peace and progress than some of the more sophisticated people…  From 'The Author's [Clifford Dobell] Epistle to the Reader: Introducing Mynheer Antony van Leeuwenhoek of Delft in Holland, Fellow of the Royal Society of London in England.'

'Antony van Leeuwenhoek and his little animals: Being Some Account of the Father of Protozoology and Bacteriology and His Multifarious Discoveries in These Disciplines' was published in 1932 which coincided with the 300th anniversary of Antony van Leeuwenhoek’s birth.  This masterpiece results from twenty-five years of vehement 'occupation' by Clifford Dobell who learned, loyalty obliges, seventeenth-century Dutch, the only language known to Leeuwenhoek.

Clifford Dobell, a respected microscopist, protozoologist and bacteriologist himself, recovered from both published and unpublished records Leeuwenhoek's observations on the protozoa and bacteria.  He chronicled Leeuwenhoek's great discoveries objectively, in fact in Leeuwenhoek's own words.  Leeuwenhoek's accurate observations and ingenuous writings undoubtedly impressed Dobell greatly.  His praise for Leeuwenhoek is displayed firmly as he writes …I have read enough to realize that those people who ridicule him are generally ignorant, and usually reveal their own incompetence in the very act of denouncing his.  Readers of 'Antony van Leeuwenhoek and his little animals' should be overwhelmed by Dobell's labor of love.  Lastly they should realize Leeuwenhoek's contribution in laying the foundations for many disciplines.  Thus true lovers of learning should value and cherish Dobell's legacy.

Samples of Leeuwenhoek's remarkable and pioneering observations in his own words are reported below, as found in Dobell's book.

Excerpts (in bold) from a letter to the Royal Society dated October 9, 1676:
They moved with bendings, as an eel swims in the water; only with this difference, that whereas an eel always swims with its head in front, and never tail first, yet these animalcules swam as well backwards as forwards, though their motion was very slow.  A note by Dobell indicates: A remarkably shrewd observation, which proves conclusively that L. was here dealing with bacteria.  Earlier in 1878 Antoine Magnin writes: … it is easy to assure one's self by the description which he has given of their form and of their movements, and by the figures which accompany these descriptions, that the organisms observed by him are truly Bacteria, Vibrios, and perhaps even Leptothrix., in Bacteria by Antoine Magnin and George Miller Sternberg, 1884, EBOOK FREE at Google Books

I saw more animalcules that had the figure of a pear, and two or three animalcules with tails.  And I perceived at this time that the pear-shaped animalcules kept not against the surface of the water, like the other creatures, but that they swan a bit deeper under water.  According to Dobell, animalcules with tails refer to Vorticella.

These curiosities of mine I divers times followed up further; and at last I saw very plainly, among other things, that from an eel which I had broken across the middle, there came out four distinct small eels, each twisted on itself, very nice and pretty, and each bigger than the one following: and the biggest, which came out first, lay and lived, and wrenched itself loose, and remain alive a little while.  A note by Dobell indicates: These were the first observations ever made on the reproduction of Anguillula.

"That is, they were shaped much like an Eel, save only that their nose A, (which was a little more opacous then the rest of their body) was a little sharper, and longer, in proportion to their body, and the wrigling motion of their body seem'd to be onely upwards and downwards, whereas that of Eels is onely side wayes: They seem'd to have a more opacous part about B, which might, perhaps, be their Gills; it seeming always the same proportionate distant from their nose, from which, to the tip of their tail, C, their body seem'd to taper."  Robert Hooke

In a letter to Hendrick van Bleyswyk dated February 9, 1702:
… in all pools and marshes, which have water standing in them in winter, but which dry up in summer, many kinds of animalcules ought to be found; and even though there were none at first in such waters, they would be brought thither by water-fowls, by way of the mud or water sticking to their feet and feathers.  A note by Dobell indicates: These remarks recall a well-known passage in 'The Origin of Species', where Darwin discusses the dispersal of organisms by similar means.

A body is pictured with its contained particles (Fig. 2, EF)
Leeuwenhoek compared the little round bodies found in the bigger ones to seeds


Image Copyright © 2003 Wim van Egmond, image use with permission
See Wim's Volvox, one of the 7 Wonders of the Micro World

As I aim at nothing but Truth, and, so far as in me lieth, to point out Mistakes that may have crept into certain matters; I hope that in so doing those I chance to censure will not take it ill: and if they would expose any Errors in my own discoveries, I'd esteem it a Service; all the more, because 'twould thereby give me Encouragement towards the Attaining of a nicer Accuracy. – Antony van Leeuwenhoek, December 25, 1700

Suggested Reading:

'The "Delft School" and the rise of general microbiology' by C. B. van Niel, in Bacteriological Reviews, 13:161-174, 1949 (free PDF at the Archive of Microbiology and Molecular Biology Reviews)

Note on Leeuwenhoek's first record of Mendelian dominance: Mendelism in the Seventeenth Century (PDF) by Clifford Dobell, Nature, 94, 588-589, 28 January 1915 (Payment is requested to read the article in full if you do not have a subscription to Nature)

MICROGRAPHIA by Robert Hooke, 1665, EText-No 15491 at Project Gutenberg

Two Leeuwenhoek-type microscopes at the Whipple Museum of the History of Science, University of Cambridge, UK