ON MICROSCOPIC DISCOVERY. 



639 



animalcules than there are people alive upon 

 the face of the whole earth at one and the 

 same time. To find the comparative size of 

 these creatures, he placed a hair of his head 

 near them, which hair through his micro- 

 scope appeared an inch in breadth ; and he 

 was satisfied that at least sixty such animal- 

 cules could lie within that diameter, whence, 

 their bodies being spherical, it must follow, 

 that two hundred and sixteen thousand of 

 them are but equal to a globe whose diameter 

 is no more than the breadth of such hair." 



Mr Leeuwenhoeck assures us that he found 

 a fluid in male spiders, which was undoubt- 

 edly their semen, and he therein discovered 

 prodigious multitudes of animalcules so ex- 

 tremely minute, that many millions of them 

 would not equal the size of a grain of millet. 

 " He found them likewise in the semen of the 

 dormouse, in oysters, in silk-worms, in the 

 Inbella minima, or small dragon fly, in the 

 common fly, in the flea, in gnats, and in 

 several other insects." It has been objected 

 to these discoveries, that no organs have been 

 detected in insects for the secretion of a 

 seminal fluid, and that Leeuwenhoeck must 

 consequently have suffered his enthusiasm to 

 deceive him into a belief that he saw what 

 nad no existence. Whether, however, secre- 

 tory organs may be detected or not, no curious 

 inquirer need remain in douht as to the fact 

 of animalcules existing in insect bodies ; and 

 from the circumstances under which they are 

 obtained, and their striking similarity, both 

 in figure and activity, to the seminal animals 

 of larger creatures, the inference is fairly 

 drawn from analogy that their character and 

 uses are the same. 



Buffon asserts that'what have been called 

 spermatic animals are not creatures really 

 possessing life, but something proper to com- 

 pose a living creature, distinguishing them 

 by the name of organic particles, and that the 

 moving bodies which are to be found in the 

 infusions either of animal or vegetable sub- 

 stance, are of the same nature. But to this 

 we may add, that all those who have examined 

 the subject with accuracy and attention, con- 

 cur in the belief that Buffon, and others who 

 adopted his views, had deceived themselves 

 by inaccurate experiments, and that Buffon 

 himself had not even seen the spermatic ani- 

 mals he supposed himself to be describing. 

 We do not altogether adopt this opinion : we 

 are inclined to think that Buffon had occa- 

 sionally seen the seminal animalcules, but it 

 was through the medium of glasses ill-adapted 

 for their development, that is to say, he observed 

 them under the confused powers of a com- 

 pound microscope of the old construction, the 

 most unsuitable instrument that could possibly 

 be employed in such researches. It is very 



evident that he saw nothing distinctly and 

 satisfactorily, or he would not have confounded 

 the spermatic animals with the gelatine 

 masses that are occasionally found in the 

 semen. He says, " We do not always see, 

 in the human semen, the filaments (tails) I 

 have mentioned : for this purpose, the liquor 

 must be examined the moment it is extracted 

 from the body ; and even then they do not 

 uniformly appear. When the liquor is too 

 thick, it presents nothing but large globules, 

 which may be distinguished with a common 

 lens. When examined with the microscope 

 they have the appearance of small oranges ; 

 they are very opaque and one of them oc- 

 cupies the whole field of the microscope." 

 He proceeds to say that after examining these 

 globules, he diluted the semen and found no- 

 thing like life or motion therein. The sum 

 of all this is, that the semen here alluded to 

 was either unhealthy and contained no ani- 

 malcules, or had been so long removed from 

 the body, that the vital germs had ceased to 

 exist, in which case they would blend with 

 the liquor and be indistinguishable ; for it is 

 a fact familiar to every observer of these 

 creatures, that when their existence is draw- 

 ing to a close they collect together in large 

 groups, and when dead form nearly a homo- 

 geneous mass. 



There is a strange degree of confusion 

 throughout Buffon's experiments and observa- 

 tions on the spermatic animals, which can 

 only be accounted for by assuming that his 

 optical resources were inadequate, and that 

 whilst he saw nothing with sufficient distinct- 

 ness to furnish data for an accurate judgment, 

 he was willing to bend all the phenomena he 

 saw to the purpose of a preconceived and 

 favourite theory. For instance, he speaks of 

 the animalcules as being attached by their 

 tails to some foreign substance, as evidently 

 striving to rid themselves of the tails, and as 

 actually accomplishing this and becoming in 

 consequence more active and lively. The 

 absurdity of these assertions is strikingly 

 shown by observation with the improved mi- 

 croscopic powers of the present day. These 

 animals are now'readily seen in all their ex- 

 tent, and in all their movements ; the tail is 

 not, as Buffon says, a mere filament, but an 

 absolute elongation of the body, gradually 

 tapering and terminating in the finest point 

 imaginable ; and the animals evidently could 

 not, if so disposed, free themselves from this 

 appendage. Their motions are, as already 

 noticed, precisely that of an eel or a serpent 

 in water ; and if at any time they appear to 

 lose their tails, it is when their motions arc 

 about to cease, when they are dying, at which 

 time they not unfrequently coil themselves 

 into a circular mass. 



