Performing the Office of Fins: Henry Baker on Volvox


Figure 27 from Baker 1764.

Figure 27 from Baker 1764.

Gilbert Smith’s foundational comparative study of the then known species of Volvox cites Henry Baker’s 1753 bookEmployment for the Microscope : in Two Parts. Although he was writing 50+ years after Van Leeuwenhoek first described his “great round particles” (see “…of the bignefs of a great corn of fand…”), Baker makes no mention of this earlier publication. Since Part II of Employment is titled “An account of various animalcules, never before described, and of many other microscopical discoveries,” it seems that he was unaware of Van Leeuwenhoek’s work [emphasis mine]. Read a Philosophical Transactions for once in your life.*

Baker has this to say about Volvox (pp. 322-324):

CHAP. XIII.

The Globe Animal

In the Month of July 1745, three Phials full of Water were sent to me from Yarmouth, by Mr. Joseph Greenleafe, having in them several Kinds of Animalcules unknown to me before. Some of the larger Kinds died in their Passage, occasioned I suppose by the Jolts they received, and a Deficiency of Air; the Phials being corked close, and too full of Water to leave them Air enough for Respiration. One kind, however, suffered very little, but when examined by the Microscope was perfectly alive and vigorous, and so numerous in one of the Phials, that the Water might be perceived to swarm with them, though their Size was much too small for the naked Eye to distinguish otherwise than as moving Points. They all died with me in two or three Days, but in that Time I had Opportunities enough to examine them, very carefully, and take a Drawing of them. My friend Mr. Arderon of Norwich sent me also, towards the End of the same Summer, some little Account with a Drawing of the same Animalcule, of which he had accidentally discovered a single one in a Drop of Water.

Fig. 27. represents this very singular minute Water Animal, as it is seen before the Microscope. Its form seems exactly globular, having no Appearance of either Head, Tail or Fins. It moves in all Directions, forwards or backwards, up or down, either rolling over and over like a Bowl, spinning horizontally like a Top, or gliding along smoothly without turning itself at all. Sometimes its Motions are slow, at other Times very swift: and when it pleases, it can turn round (as it were upon an Axis) very nimbly, without removing out of its place. Its whole body is transparent, except where the circular black Spots are shewn in the Picture ; of which Spots some had six of seven, some one, two three, four or five, and others none at all. These probably are its Eggs or young ones : but the short Time they were with me, prevented my coming to a Certainty as to this Particular. The Surface of the whole Body appeared in some as if all over dotted with little Points, and in others as if granulated like Shagreen: but their more general Appearance was, as if beset thinly round with shortly moveable Hairs or Bristles ; and ’tis not improbable all their Motions may be produced by some such Instruments, performing the Office of Fins.

Good guess! As far as I know, this is the first suggestion of flagella in Volvox.

I had to look up shagreen; it’s a kind of rough leather often made from shark skin.

*Yeah, I’m finally watching Archer.

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