on the Equivocal Production of Animals. 393 



whenever it is made, in a few hours the worms become as lively as 

 when first taken from the corn. When seed-corn has this ear- 

 cockle applied to it, and is sown, it becomes inoculated, and the 

 worm grows in its substance, and passes along the inside of the 

 stalk in the sap, so as to be found in the seed produced. * 



Sharp needles frequently make their way through the fleshy 

 parts of the body, in a very singular manner, and may not the infi- 

 nitely more minute, and needle-shaped eggs of Entozoa, make a 

 similar progress ? The power of retaining life in some of the more 

 minute animals and their eggs, is also highly favourable to the idea 

 of their transmission and long preservation. Lewenhoek kept a 

 cheese maggot glued to the point of a pin for many weeks, and it 

 still retained life. The Rotatoria, or wheel animal, can be reviv- 

 ed by a drop of water, after having lain in the dry state for a year 

 apparently dead ; and the eggs of various insects deposited in fleshy 

 substances, resist washing, boiling, and other various modes <rf cook- 

 ery, without their powers of life being destroyed, t 



Among other probable means of the transmission of the minute 

 eggs of Entozoa, or even the young of the viviparous species, may 

 be enumerated : 



1. Transmission by the food. This may occur accidentally in 

 any kind of diet ; or when we reflect that many species of worms 

 are common to man and other animals, whose flesh and entrails are 

 daily used in diet, J the probability of the transmission is rendered 

 even greater. 



2. By water and drinks, and even by inhalation and absorption 

 of the minute ova. 



3. By direct transmission, as in the case of Oxyures, while at 

 stool in water-closets, &c. ; these worms having the power of leap- 

 ing, and of very quick and active motion. 



On the whole, therefore, the first proposition of Bremser, that 

 the eggs of intestinal worms cannot come from without, seeing we 

 cannot distinctly trace their progress, is untenable, because it is an 

 assertion without proof, and because there appears to be no physi- 

 cal impossibility to such transmission ; but, on the contrary, many 

 probable means by which it may be accomplished. The second ar- 

 gument of Bremser is drawn from the analogy of the infusory ani- 

 mals. Those minute animalcula found in vinegar, in paste, and 

 some other substances, he supposes derive their origin from the 

 process of fermentation. This, too, is but an assumption. The 

 extreme minuteness of these animals, which are only rendered visi- 

 ble by the aid of the microscope, preclude us from investigating 



" Comparative Anat. Vol. I. p. 368. 



•f- Spallanzani found a live worm in the body of a fish which had been boiled. 

 (Tracts on the Nat. Hist, of Animals and Vegetables.) 



% The Ascaris lumbricoides is common to the ox ancl sheep, as well as to man. 

 The Distoma hepaticum, Cysticercus, and Echinococcus, are common to man and 

 the sheep, &c — RuDOL. Entoz. System. 



