44 



the Conferva?, and that both the cells and the parts they 

 form have vitality. What we are in quest of is the con- 

 dition of such growth by multiplication of cells, which is 

 essential to their forming a germ-mass and laying the 

 foundation of a future individual ; and our conception of 

 this condition will be in the ratio of our comprehension 

 of the purport of the process by which the germ-mass is 

 formed in all animals. 



When we find the development of the Aphis by multi- 

 plication of cells, and its continuous growth by the meta- 

 morphosis of the resulting germ-mass, taking place within 

 the body of the larval Aphis, without the concurrent agency 

 of male and female sexual organs, and without any previous 

 detachment of an ovum properly so called, or any pre- 

 existent ovum, like that in the larviparous Blue-bottle Fly, 

 we recognise a phenomenon essentially similar to the pro- 

 cess which by multiplication of cells in so-called ( continuous 

 growth 5 developes the uncinated arid suctorious head and 

 neck from the common cyst of the Ccenurm*, and which 

 produces the bud in the adult Hydra viridis and in the larval 

 Hydra Tuba. But in the Aphis the gemmation, instead of 

 protruding through the side of the abdomen, extends into 

 an oviduct ; the progressive growth distends the tube into 

 a uterine sac, and the progeny escapes 'per vaginam. 5 



The presence of female organs determines the sex of this 

 viviparous larva, and by this analogy Prof. Steenstrup may 

 havebeen guided to the opinion that the gemmiparous larva? 

 of the Medusas and other species, which he calls f Arnme/ 

 were females. Dr. Carpenter affirms that " he had no more 

 reason for so calling them than the botanist would have in 

 speaking of a budding plant as of the female sex up to the 

 time of the evolution of the flowering system." (p. 194.) 

 And this will seem to be true to the botanist who may 

 view such a plant as an individual whole, with its nutritive, 



* H. D. Goodsir, 'On the Development, &c. of the Acephalocysts/ 

 Trans. Royal Soc. of Edinburgh, 1844, vol. xv. p. 565, pi. 16. 



