HARDWICKE'S SCIENCE-GOSSIP. 



2<> 



requested some of those who advocated the spon- 

 taneous generation theory to procure him some 

 weevils, and accordingly, on the 13th of March, he 

 received some grains of wheat (many of which had 

 their insides eaten away) mixed with weevils. 



The following is Leeuwenhoek's description of 

 his experiments. " I took three glasses, in each of 

 which I put six, eight, or nine weevils, and eight, 

 ten, or twelve grains of wheat, which wheat I was 

 the more assured could not be infected because it 

 had been kept for several months closely covered up 

 in my study. In the fourth glass I put some weevils 

 without any wheat, but this last mode of experiment 

 I afterwards rejected, observing that in twelve days 

 they all died. As to the other three glasses, the 

 weather being cold and observing the animals for 

 the most part to be motionless, I put them into a 

 leather case which I always carried about me. And 

 I had no doubt but I should clearly prove to all 

 that the weevil proceeds from a maggot, for which 

 reason I frequently examined these objects by the 

 microscope. 



" I at first entertained an opinion that the weevil, 

 like the silkworm moth and many other insects, did 

 not, while in that shape, take any food ; but herein 

 I found myself mistaken, and observed that the 

 weevil not only feeds upon wheat, but that it can 

 excavate or scoop out the contents of every grain 

 and creep about in the inside, being provided with 

 a beak or trunk of a great length in proportion to 

 the size of the body, at the extremity of which are 

 certain exceedingly small orgaus or instruments like 

 teeth, and with these it can bore or pierce through 

 the outward husk or shell of the wheat, and thus 

 open to itself a passage to devour the contents." 



After the lapse of a fortnight he observed the 

 impregnation of a female weevil, and in about two 

 months his patience was rewarded by the discovery 

 of two short and thick little maggots, one of them 

 about the size of a large grain of sand ; and on 

 examining other grains of wheat by the aid of a 

 microscope, he observed minute punctures, and on 

 opening the wheat he found a perfectly-formed 

 weevil of a yellow colour. Upon dissecting a female, 

 he found five white eggs. He gives figures of the 

 egg maggot " beak or trunk," and part of the head 

 showing the compound eyes, and which he com- 

 pares to ".a parcel of very minute black coral beads 

 placed in exact order close together, and this I con- 

 cluded to be one of the eyes. 



" I trust that these experiments and observations 

 will prove that weevils cannot be produced otherwise 

 than by propagation and laying eggs, from which 

 eggs maggots proceed, and finally those maggots 

 are changed into weevils." 



He seems — to use a cant phrase — to have been 

 " exercised " by the incredulity of the " vulgar," as 

 will be seen from the following remarks : — " But 

 whether the vulgar will be hereby convinced of the 



error of their opinion in this respect I much doubt, 

 being continually pestered with their objections to 

 what I have advanced. It is, however, with me a 

 certain truth that what I have demonstrated re- 

 specting the weevil— namely, that it cannot be 

 produced otherwise than by generation — does also 

 hold good with regard to all creatures endued with 

 life and motion. Probably what l I here advance 

 may appear strange to some, and they may, perhaps, 

 wish me to inquire into the propagation of other 

 minute animals; but for the present 1 leave tire 

 prosecution of these matters to those who may 

 choose to bestow as much labour thereon as I have 

 done in this examination of the weevil, assuring 

 them that my observations are the result of more 

 than four mouths' application to the subject." 



Leeuwenhoek's microscopic studies will generally 

 be found to have had a practical bearing. After 

 his examination of the infected wheat and the 

 weevil, he advises the frequent shifting of the grain, 

 which he says will prevent the multiplication of this 

 pest ; and he gives the following reasons for this 

 advice:— " Supposing one of these insects to have 

 pierced and prepared two or three grains ready to 

 deposit its eggs, and soon after the corn is moved 

 or spread about, the animal, when it is ready to lay 

 an egg, finding no grain prepared to receive it, must 

 leave such egg on the outside of the corn, where the 

 young maggot, when hatched, will be in the same 

 situation as seed sown in barren land, and, con- 

 sequently, must perish. But if such corn is undis- 

 turbed the weevil may multiply in a great degree 

 by depositing its eggs in the grains fully prepared 

 to receive them, and which may be considered as so 

 many nests for the reception of the young." 



Leeuwenhoek does not, however, long refrain 

 from combating the heterogenists. His essay on 

 the weevil is succeeded by one " On the Maggot or 

 Caterpillar infesting Corn in granaries ; the Nature 

 of its Generation explained, and the means to pre- 

 vent its increase pointed out." 



" Having, as I hope, by my observations on the 

 weevil, convinced mankind that it is propagated in 

 the ordinary way of generation, I have since em» 

 ployed myself on the examination of that insect or 

 maggot which our bakers and corn-dealers name dc 

 wolf." * This creature is a very small white maggot 5 

 provided with pincers and teeth placed on the fore 

 part of its head, by which it not only feeds on and 

 consumes wheat and other grain, but also can per- 

 forate or gnaw holes in wood. The common opinion 

 is that it is produced from corruption or else from 

 what is called "blight." In order to refute this 

 "vulgar error," he carries on a series of experi- 

 ments similar to those described in the essay 

 on the weevil; and he found that the maggot 



* " The Wolf, " From a note it appears that this pest was 

 scarcely known in England. 



