ROTIFERA. 3 1 



animal and vegetable matter with a hundred-stomach power. That 

 low delight, the bliss supreme of the civilised gourmand, is given 

 most liberally where it ought to be, to the creatures at the lowest 

 grade of animalitj^ 



Nor is the procreative function so abundantly or so variously en- 

 joyed by any other animal as in the Polygastria. At once fissiparous, 

 gemmiparous, and oviparous, the androgynous organs for the de- 

 velopment of the fertile ova were, as shown in the preceding Lecture, 

 of a sufficiently complicated charactei% In creatures whose most 

 obvious and common mode of propagation is by spontaneous fission, 

 a power so actively exercised, as, according to Ehrenberg's ex- 

 periments, to be productive of an incalculably rapid rate of multipli- 

 cation, it may be demanded : To what end were special organs of 

 generation developed ? Why should these fissiparous Polygastria be 

 provided with male glands, vesiculse seminales, and reticulated ovaria ; 

 with normal reproductive organs almost as complicated as in the 

 snail, which has no other mode of generation than by fertile ova ? 

 I am apt to think that the fissiparous reproduction has reference 

 principally to increasing the numbers of individuals in the infusions, 

 or receptacles of decaying organisms, in which they at that time 

 exist ; whilst the development of fertile ova has relation to futui^e and 

 diflTerent localities or collections of such infusions, into which the ova 

 may be conveyed more easily than the entire animals, and so lay the 

 foundation of new generations of Infusoria. In the heats of summer, 

 for example, many of the pools and stagnant collections of water in 

 which Infusoria abound are dried up. Now, it is true, that certain 

 Infusoria have the power of retaining their vitality for a long time in 

 a state of desiccated torpidity. I shall presently have to allude to 

 the experiments of Spalanzani and others on the wheel-animalcules, 

 in illustration of this curious property. Some who have repeated his 

 experiments have not succeeded in reviving the subjects after so long 

 a period of inanimation : nevertheless, great tenacity of life is un- 

 questionably, notwithstanding the delicate tissues of the Infusoria, 

 a property of creatures of their grade of organisation ; and what holds 

 good of the parent, in regard to this property of latent life, must, a 

 fortiori, be allowed to the ovum. 



Now the act of oviparous generation, that sending forth of countless 

 ova through the fatal laceration or dissolution of the parent's bodj-, 

 is most commonly observed in the well-fed Polygastria, which crowd 

 together as their little ocean evaporates ; and thus each leaves, by the 

 last act of its life, the means of perpetuating and dift'using its species 

 by thousands of fertile germs. When the once thickly tenanted pool 

 is dried up, and its bottom converted into a layer of dust, these in- 



