XLVI. Before I finish this chapter I shall relate the experiments of Mr. Needham on the seed of a kind of cuttle fish, called calmar. This able naturalist having sought for spermatic animals in the milts of many different fish, found them in the roe of a calmar, apparent to the naked eye. During the summer he dissected calmars at Lisbon, but found no appearance of any roe, nor any reservoir which appeared to be destined for the reception of the seminal liquor; and it was in the middle of December that he began to discern the first traces of a new vessel replete with a milky juice. This reservoir increased, and the seed which it contained was diffused very abundantly. By examining this liquor with the microscope, he perceived only small opaque globules, which floated in a kind of serous matter, without the least appearance of life. But some time after, in the milt of another calmar, he found these organic parts completely formed; they seemed like spiral springs shut up in a kind of transparent case. They appeared as perfect at first as they did at last, excepting that by degrees they contracted and formed a kind of screw. The lid of the case was a species of valve that opened outwardly, and by which all the contents might issue; it contained another valve, a barrel, and a spongy substance; therefore the whole machine consisted in an external, transparent, and cartilaginous case, whose upper extremity is terminated by a round head, formed by the case itself, and which performs the office of a valve. In this external case is contained a transparent tube, which encloses the spring, piston, or valve, barrel, or spongy substance. The screw occupies the upper part of the tube and case, the piston and barrel are placed in the middle, and the spongy substance occupies the lower part. These machines pump up the lacteal liquor, of which the spongy substance is full; and before the animal spawns, the whole milt is no more than a composition of these organic parts, which have absolutely pumped up the lacteal liquor. As soon as these little machines are taken from the body of the animal, and deposited either in water, or held in the air, they begin to act; the spring ascends, followed by the piston, the barrel, and the spongy substance which contains the liquor; and as soon as the spring and the tube which contain it begin to quit the case, the spring folds up; and all that remains within begins to move, till the spring, the sucker, &c. are entirely come out: as soon as that is done, the remainder immediately follow, and the lacteal liquor, which has been pumped out, and which was contained in the spongy substance flows out by the barrel.
As this observation is very singular, and incontestibly proves that the moving bodies found in the milt of the calmar are not animals, but simple machines, a kind of pumps, I have deemed it necessary to give Mr. Needham's own words.[Q]
[Q] See New Discoveries made with the microscope by Mr. Needham, chap. vi. Leyden, 1747.
"When the small machines, he says, are arrived to their perfect maturity, many of them act the moment they are in the open air; nevertheless most of them may be commodiously placed, so as to be seen with a microscope, before their action begins; and even to make them act, the upper extremity of the external case must be moistened with a drop of water which then begins to expand, while the two small ligaments which issue from the case twist and turn in different manners: at the same time, the screw ascends slowly, the volutes, which are at its upper end, approach and act against the top of the case: those at the bottom also advance, and seem to be continually followed by others which come from the piston. I say, they seem to be followed, because I do not think they are so effectually, but only a deception produced by the nature and motion of the screw. The piston and barrel also follow the same direction, extend lengthways, and at the same time move towards the top of the case, which is perceived by the vacuum at the bottom. As soon as the screw, with the tube in which it is enclosed, begins to appear externally from the case, it folds, because it is retained by its two ligaments: nevertheless, all the internal contents continue to move gently and gradually, until the screw, piston, and bladder, are entirely come out. When that is done, the rest follow directly after. The piston separates from the barrel, and the apparent ligament, which is below the latter, swells and acquires a diameter equal to that of the spongy substance which follows it. This, although much larger than when in the case, becomes still five times longer than before. The tube which incloses it all is straightened in its middle, and forms two kinds of knots, about a third of its length distant from each extremity: the semen then flows through, and is composed of small opaque globules, which float in a serous matter, without shewing any signs of life, and which are precisely such as I have said to have seen them when they were diffused in the reservoir of the milt. In the figure, the part between the two knots seems to be broken: when it is examined attentively, we find that what causes it to appear as such, is, that the spongy substance with in the tube is broken in nearly equal pieces, which the following phenomena will clearly prove. Sometimes it happens, that the screw and the tube break by the piston, which remains in the barrel; then the tube closes in a moment, and takes a conical figure, by contracting, as much as it is possible, above the end of the screw, which demonstrates its great elasticity in that part: and the manner in which it accommodates itself with the figure of the substance it incloses, when it receives the least change, proves, that it is equal in every other respect."
Mr. Needham from this conceives that we might imagine the actions of all this machine were owing to the spring of the screw, but he proves, by many experiments, that the screw, on the contrary, only obeys a power which resides in the spongy part. As soon as the screw is separated from the rest, it ceases its action, and loses all its activity. The author afterwards makes this reflection on this singular machine:
"If, says he, I had seen the animalcule pretended to be in the semen of living animals, perhaps I might be in a condition to determine whether they are really living creatures, or simple machines prodigiously minute, and which are in miniature, what the vessels of the calmar are in the great."
By this, and some other analogies, Mr. Needham concludes, there is a great appearance that the spermatic worms of other animals are only organized bodies and machines, like to those of the calmar, whose actions are made at different times; "for, says he, let us suppose, that in the prodigious number of spermatic worms seen on the table of a microscope, there are some thousands which act at the same time, that will be sufficient to shew us, they are all alive. Let us also conceive, adds he, that the motion of these spermatic worms remains, like that of the machines of the calmar, about half a minute; then the succession of action of these small machines, will remain a long time, and the pretended animals will appear to decrease successively. Besides why should the calmar alone have machines in its seed, whereas every other animal has spermatic worms, and real animals? Analogy is here of such great weight, that it does not appear possible to refuse it." Mr. Needham likewise very justly remarks, that even the observations of Leeuwenhoek, seems to indicate that the spermatic worms have a great resemblance with the organized bodies in the seed of the calmar. "I have, says Leeuwenhoek, speaking of the cod, taken those real substances for hollow and extended animalcule, because they were four times as large as the living animalcule." And in another part, "I have remarked, he says, speaking of the seed of a dog, that the animalcules often change their form, especially when the liquor in which they float evaporates. The progressive motion does not extend above the diameter of a hair."[R]
[R] See Leeuwenh. Arch. Nat. page 306, 309, 310.
After considering all these circumstances Mr. Needham conjectures, that the supposed spermatic animals might possibly be only natural machines, substances much more simply organized than the bodies of animals. I have seen with the microscope, these machines in the calmar, and the description he gives of them, is very faithful and exact. His observations then shew us, that the seminal liquor is composed of parts which seek to be organized; that it, in fact, produces organized substances, but that they are not as yet, either animals or organized substances, like the individual which produced them. We might suppose, that these substances are only instruments which serve to perfect the seminal liquor, and strongly impel it; and that it is by their brisk and internal action, that it most intimately penetrates the seminal liquor of the female.