192 Natural History of ilntozoa. 



see an individual splitting himself into two parts, each rapidly 

 becoming a perfect creature of its sort. In the case of the 

 dividmg animalcule, the process is patent to all who look 

 on ; but the aphis riddle was only deciphered by great labour 

 and pains. A female aphis, retaining her spinsterhood and 

 virginity, gives birth to a succession of infants like herself, and 

 only towards the close of the season does she take a husband, 

 and set about the business of family-making by the orthodox 

 method of fecundated eggs. It required the collection of a 

 great many scattered facts to account for such proceedings, but 

 it was discovered that the little ones produced by the aphis 

 spinster were repetitions of herself by a process much like the 

 budding of plants. We usually find a bud remaining attached 

 to the parent plant, and growing up to maturity without leaving 

 its mamma. This remaining with the parent is not, however, 

 necessary, as the gardener shows when he removes a bud and 

 causes it to grow in another place. Certain water plants 

 also drop buds or bulbils, which, if they fall in suitable quarters, 

 gradually grow to the parent form. Plants grown from buds 

 produce fresh buds in their turn, and animals grown from buds 

 have a similar power of repetition. 



Up to the present we have only considered instances of 

 offspring of the bud kind, which resemble their parents as soon 

 as they are mature ; but Nature furnishes us with a vast number 

 of instances in which this kind of offspring developes into some- 

 thing so unlike its parent, that it could never be imagined to 

 proceed from it, if the fact that it did so was not well ascer- 

 tained. H would take us into too wide a field of inquiry to 

 pursue this investigation at large, but we have arrived at two 

 important facts* — first, that certain creatures give rise to 

 offspring that bear the same relation to the parent that a bud 

 does to the tree from which it grows ; and, secondly, that these 

 budded children may grow up to resemble, or not to resemble 

 the parent form. In many cases such creatures do not contain 

 the organs required for reproduction by true eggs. If these 

 facts are borne in mind we shall be able to understand certain 

 highly curious proceedings of the intestinal worms. Let us, 

 for example, follow Dr. Cobbold's account of the fluke worm, 

 called Distoma militaire. The readers of the Intellectual 

 Observer need not be told what a " fluke " is, and if any have 

 forgotten it, let them turn to an article by Dr. Cobbold (vol. i. 

 p. 25). 



Eeferring to the splendid workf which Dr. Cobbold has just 



* Those who wish to pursue this inquiry, should read Professor Lawson's 

 translation of Quatrefiige's Metamorphoses of Man and Animals. 



f Entozoa : an Introduction to the Study of Uelminthologij, with reference 

 more particularly to the Internal Parasites of Man. By T. Spencer Cobbold, 

 M.D., F.R.S., Lecturer on Comparative Anatomy at the Middlesex Hospital. 

 Groombridge and Sons, Paternoster Row. 



